<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.2 20190208//EN" "http://jats.nlm.nih.gov/publishing/1.2/JATS-journalpublishing1.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" dtd-version="1.2" xml:lang="en">
    <front>
        <journal-meta>
            <journal-id journal-id-type="pmc">F1000Research</journal-id>
            <journal-title-group>
                <journal-title>F1000Research</journal-title>
            </journal-title-group>
            <issn pub-type="epub">2046-1402</issn>
            <publisher>
                <publisher-name>F1000 Research Limited</publisher-name>
                <publisher-loc>London, UK</publisher-loc>
            </publisher>
        </journal-meta>
        <article-meta>
            <article-id pub-id-type="doi">10.12688/f1000research.174779.1</article-id>
            <article-categories>
                <subj-group subj-group-type="heading">
                    <subject>Research Article</subject>
                </subj-group>
                <subj-group>
                    <subject>Articles</subject>
                </subj-group>
            </article-categories>
            <title-group>
                <article-title>Beyond the Beauty: Meristic and Genomic Signatures of Bangka&#x2019;s Endemic Betta Fishes</article-title>
                <fn-group content-type="pub-status">
                    <fn>
                        <p>[version 1; peer review: 2 approved with reservations]</p>
                    </fn>
                </fn-group>
            </title-group>
            <contrib-group>
                <contrib contrib-type="author" corresp="no">
                    <name>
                        <surname>Helmizuryani</surname>
                        <given-names>Helmizuryani</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Conceptualization</role>
                    <role content-type="http://credit.niso.org/">Data Curation</role>
                    <role content-type="http://credit.niso.org/">Investigation</role>
                    <role content-type="http://credit.niso.org/">Methodology</role>
                    <role content-type="http://credit.niso.org/">Writing &#x2013; Original Draft Preparation</role>
                    <role content-type="http://credit.niso.org/">Writing &#x2013; Review &amp; Editing</role>
                    <xref ref-type="aff" rid="a1">1</xref>
                </contrib>
                <contrib contrib-type="author" corresp="no">
                    <name>
                        <surname>Hidayat</surname>
                        <given-names>Saleh</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Data Curation</role>
                    <role content-type="http://credit.niso.org/">Investigation</role>
                    <role content-type="http://credit.niso.org/">Methodology</role>
                    <role content-type="http://credit.niso.org/">Validation</role>
                    <xref ref-type="aff" rid="a2">2</xref>
                </contrib>
                <contrib contrib-type="author" corresp="no">
                    <name>
                        <surname>Nizar</surname>
                        <given-names>Muhammad</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Data Curation</role>
                    <role content-type="http://credit.niso.org/">Investigation</role>
                    <role content-type="http://credit.niso.org/">Methodology</role>
                    <role content-type="http://credit.niso.org/">Validation</role>
                    <uri content-type="orcid">https://orcid.org/0000-0002-9045-6444</uri>
                    <xref ref-type="aff" rid="a1">1</xref>
                </contrib>
                <contrib contrib-type="author" corresp="no">
                    <name>
                        <surname>Prasetyo</surname>
                        <given-names>Andhika Prima</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Investigation</role>
                    <role content-type="http://credit.niso.org/">Validation</role>
                    <uri content-type="orcid">https://orcid.org/0000-0002-7412-8432</uri>
                    <xref ref-type="aff" rid="a3">3</xref>
                </contrib>
                <contrib contrib-type="author" corresp="no">
                    <name>
                        <surname>Muslimin</surname>
                        <given-names>Boby</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Data Curation</role>
                    <role content-type="http://credit.niso.org/">Formal Analysis</role>
                    <role content-type="http://credit.niso.org/">Investigation</role>
                    <role content-type="http://credit.niso.org/">Validation</role>
                    <role content-type="http://credit.niso.org/">Writing &#x2013; Original Draft Preparation</role>
                    <role content-type="http://credit.niso.org/">Writing &#x2013; Review &amp; Editing</role>
                    <uri content-type="orcid">https://orcid.org/0000-0002-0662-9972</uri>
                    <xref ref-type="aff" rid="a3">3</xref>
                </contrib>
                <contrib contrib-type="author" corresp="no">
                    <name>
                        <surname>Zamroni</surname>
                        <given-names>Mochammad</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Data Curation</role>
                    <role content-type="http://credit.niso.org/">Investigation</role>
                    <role content-type="http://credit.niso.org/">Methodology</role>
                    <role content-type="http://credit.niso.org/">Validation</role>
                    <uri content-type="orcid">https://orcid.org/0000-0001-8029-8764</uri>
                    <xref ref-type="aff" rid="a4">4</xref>
                </contrib>
                <contrib contrib-type="author" corresp="no">
                    <name>
                        <surname>Astuti</surname>
                        <given-names>Dessy Nurul</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Data Curation</role>
                    <role content-type="http://credit.niso.org/">Investigation</role>
                    <role content-type="http://credit.niso.org/">Validation</role>
                    <xref ref-type="aff" rid="a4">4</xref>
                </contrib>
                <contrib contrib-type="author" corresp="no">
                    <name>
                        <surname>Swarlanda</surname>
                        <given-names>Swarlanda</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Data Curation</role>
                    <role content-type="http://credit.niso.org/">Investigation</role>
                    <role content-type="http://credit.niso.org/">Methodology</role>
                    <role content-type="http://credit.niso.org/">Validation</role>
                    <xref ref-type="aff" rid="a5">5</xref>
                </contrib>
                <contrib contrib-type="author" corresp="no">
                    <name>
                        <surname>Ramadhanu</surname>
                        <given-names>Destra</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Data Curation</role>
                    <role content-type="http://credit.niso.org/">Investigation</role>
                    <role content-type="http://credit.niso.org/">Methodology</role>
                    <role content-type="http://credit.niso.org/">Validation</role>
                    <xref ref-type="aff" rid="a5">5</xref>
                </contrib>
                <contrib contrib-type="author" corresp="yes">
                    <name>
                        <surname>Nurhidayat</surname>
                        <given-names>Luthfi</given-names>
                    </name>
                    <role content-type="http://credit.niso.org/">Data Curation</role>
                    <role content-type="http://credit.niso.org/">Formal Analysis</role>
                    <role content-type="http://credit.niso.org/">Software</role>
                    <role content-type="http://credit.niso.org/">Writing &#x2013; Original Draft Preparation</role>
                    <role content-type="http://credit.niso.org/">Writing &#x2013; Review &amp; Editing</role>
                    <uri content-type="orcid">https://orcid.org/0000-0002-0625-2984</uri>
                    <xref ref-type="corresp" rid="c1">a</xref>
                    <xref ref-type="aff" rid="a6">6</xref>
                </contrib>
                <aff id="a1">
                    <label>1</label>Study Program of Aquaculture, Faculty of Agriculture, Universitas Muhammadiyah Palembang, Palembang, South Sumatra, 30263, Indonesia</aff>
                <aff id="a2">
                    <label>2</label>Study Program of Biology Education, Faculty of Teacher Training and Education, Universitas Muhammadiyah Palembang, Palembang, South Sumatra, 30263, Indonesia</aff>
                <aff id="a3">
                    <label>3</label>Research Center for Applied Zoology, National Research and Innovation Agency, Cibinong, West Java, 16911, Indonesia</aff>
                <aff id="a4">
                    <label>4</label>Research Center for Biota System, National Research and Innovation Agency, Cibinong, West Java, 16911, Indonesia</aff>
                <aff id="a5">
                    <label>5</label>Yayasan Ikan Endemik Bangka Belitung, Pangkal Pinang, Bangka Belitung Island, 33123, Indonesia</aff>
                <aff id="a6">
                    <label>6</label>Faculty of Biology, Universitas Gadjah Mada, Sleman, Special Region of Yogyakarta, 55281, Indonesia</aff>
            </contrib-group>
            <author-notes>
                <corresp id="c1">
                    <label>a</label>
                    <email xlink:href="mailto:luthfibio@ugm.ac.id">luthfibio@ugm.ac.id</email>
                </corresp>
                <fn fn-type="conflict">
                    <p>No competing interests were disclosed.</p>
                </fn>
            </author-notes>
            <pub-date pub-type="epub">
                <day>10</day>
                <month>2</month>
                <year>2026</year>
            </pub-date>
            <pub-date pub-type="collection">
                <year>2026</year>
            </pub-date>
            <volume>15</volume>
            <elocation-id>226</elocation-id>
            <history>
                <date date-type="accepted">
                    <day>30</day>
                    <month>1</month>
                    <year>2026</year>
                </date>
            </history>
            <permissions>
                <copyright-statement>Copyright: &#x00a9; 2026 Helmizuryani H et al.</copyright-statement>
                <copyright-year>2026</copyright-year>
                <license xlink:href="https://creativecommons.org/licenses/by/4.0/">
                    <license-p>This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</license-p>
                </license>
            </permissions>
            <self-uri content-type="pdf" xlink:href="https://f1000research.com/articles/15-226/pdf"/>
            <abstract>
                <sec>
                    <title>Background</title>
                    <p>The genus 
                        <italic toggle="yes">Betta</italic> (family Osphronemidae) comprises over 70 species, many of which are endemic to Southeast Asia and highly vulnerable to habitat loss. While 
                        <italic toggle="yes">Betta splendens</italic> is well studied due to its importance in the ornamental fish trade, most wild 
                        <italic toggle="yes">Betta</italic> species remain poorly characterized, particularly at the genomic level. The Bangka Islands of Indonesia harbor several endemic 
                        <italic toggle="yes">Betta</italic> species threatened by peatland degradation.</p>
                </sec>
                <sec>
                    <title>Methods</title>
                    <p>We conducted an integrated meristic and genomic comparison of three endemic Bangka Island species&#x2014;
                        <italic toggle="yes">Betta burdigala</italic>, 
                        <italic toggle="yes">B. chloropharynx</italic>, and 
                        <italic toggle="yes">B. schalleri.</italic> Specimens were collected from peatland waters in Bangka, and meristic traits were examined to confirm diagnostic characteristics. High-molecular-weight DNA was extracted and sequenced using Oxford Nanopore PromethION technology, followed by 
                        <italic toggle="yes">de novo</italic> assembly and reference-guided scaffolding using the 
                        <italic toggle="yes">Betta splendens</italic> genome.</p>
                </sec>
                <sec>
                    <title>Results</title>
                    <p>The meristic analysis confirmed features consistent with their taxonomic placement within the 
                        <italic toggle="yes">coccina</italic>, 
                        <italic toggle="yes">waseri</italic>, and 
                        <italic toggle="yes">pugnax</italic> groups. Genome assembljies were highly contiguous and complete (BUSCO &gt;97%), with 
                        <italic toggle="yes">B. chloropharynx</italic> showing the largest genome size, highest scaffold N50, and elevated retrotransposon content. Gene duplication analysis revealed dispersed duplications as the dominant category across all genomes, with variation in tandem and proximal duplicates. Comparative genomic analysis demonstrated high collinearity, with 
                        <italic toggle="yes">B. chloropharynx</italic> and 
                        <italic toggle="yes">B. schalleri</italic> showing the closest relationship, while 
                        <italic toggle="yes">B. burdigala</italic> diverged earlier. The Colony Stimulating Factor 1 Receptor A (CSF1RA) protein phylogenetic tree closely resembles the phylogenetic tree of nine fish species based on NCBI taxonomic data. We also identified two massive protein insertions in the CSF1RA of 
                        <italic toggle="yes">B. burdigala.</italic>
                    </p>
                </sec>
                <sec>
                    <title>Conclusions</title>
                    <p>This study provides morphological and genomic evidence supporting the distinctiveness of Bangka&#x2019;s endemic 
                        <italic toggle="yes">Betta</italic> species and delivers essential genomic resources for evolutionary research and conservation of these endangered freshwater fishes.</p>
                </sec>
            </abstract>
            <kwd-group kwd-group-type="author">
                <kwd>Betta burdigala</kwd>
                <kwd>Betta chloropharynx</kwd>
                <kwd>Betta schalleri</kwd>
                <kwd>meristic analysis</kwd>
                <kwd>genome assembly</kwd>
                <kwd>synteny</kwd>
                <kwd>conservation genomics</kwd>
                <kwd>Bangka Island</kwd>
            </kwd-group>
            <funding-group>
                <award-group id="fund-1" xlink:href="https://doi.org/10.13039/501100009509">
                    <funding-source>Kementerian Riset Teknologi Dan Pendidikan Tinggi Republik Indonesia</funding-source>
                    <award-id>123/C3/DT.05.00/PL/2025</award-id>
                </award-group>
                <funding-statement>123/C3/DT.05.00/PL/2025</funding-statement>
                <funding-statement>
                    <italic>The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.</italic>
                </funding-statement>
            </funding-group>
        </article-meta>
    </front>
    <body>
        <sec id="sec5" sec-type="intro">
            <title>Introduction</title>
            <p>The genus 
                <italic toggle="yes">Betta</italic> (family Osphronemidae) includes over 70 recognized species, many of which are endemic to Southeast Asia. Despite the global popularity of the domesticated Betta splendens in the ornamental fish trade, the majority of wild Betta species remain under-researched. The number of endemic wild Betta distribution and diversity of Southeast Asia has been identified for 16 years in Thailand (2 species) and Indonesia (9 species).
                <sup>
                    <xref ref-type="bibr" rid="ref1">1</xref>&#x2013;
                    <xref ref-type="bibr" rid="ref5">5</xref>
                </sup> The high levels of endemism and restricted ranges of many Betta species make them particularly vulnerable to habitat loss and environmental changes.
                <sup>
                    <xref ref-type="bibr" rid="ref2">2</xref>,
                    <xref ref-type="bibr" rid="ref5">5</xref>
                </sup>
            </p>
            <p>The Bangka Islands, located off the east coast of Sumatra, are home to several unique Betta species adapted to specialized freshwater habitats such as peat swamps and slow-moving forest streams. Three species of Betta spp. were endemic, i.e., 
                <italic toggle="yes">Betta burdigala</italic>, 
                <italic toggle="yes">Betta chloropharynx</italic>, and 
                <italic toggle="yes">Betta schalleri.</italic>
                <sup>
                    <xref ref-type="bibr" rid="ref1">1</xref>
                </sup> According to IUCN red list, the conservation status for them were criticaly endangered and endangered. The lack of molecular resources poses a barrier to implementing effective conservation strategies for these fishes. The genetic studies of the endemic fish Betta spp. on Bangka Island have been conducted in mitochondrial DNA analysis, eDNA metabarcoding, and comprehensive morphological examinations, which are needed to confirm the genetic relationships and taxonomic status of these species. However, the whole genome for the evolution of the endemic fish Betta spp. on Bangka Island hasn&#x2019;t been revealed.
                <sup>
                    <xref ref-type="bibr" rid="ref6">6</xref>
                </sup>
            </p>
            <p>Genome assemblies are indeed foundational resources for advancing biological research and conservation management. They provide critical insights into genetic diversity, evolutionary biology, and species conservation strategies. High-quality genomic data could be used for Long-read sequencing and high-throughput chromosome (Hi-C) technology. Long-read sequencing technologies are essential for producing high-quality genome assemblies. These technologies help resolve complex repeats and haplotype heterozygosity, which are sources of assembly errors.
                <sup>
                    <xref ref-type="bibr" rid="ref7">7</xref>
                </sup> Hi-C confirmation capture that enables contiguous genome assemblies.
                <sup>
                    <xref ref-type="bibr" rid="ref8">8</xref>
                </sup> Genome assemblies could be informative evidence for scientific management decisions and tools for understanding the basis of genetic adaptation in various species.
                <sup>
                    <xref ref-type="bibr" rid="ref9">9</xref>,
                    <xref ref-type="bibr" rid="ref10">10</xref>
                </sup>
            </p>
            <p>Bangka Island presents a unique opportunity to investigate the genetic foundations of adaptation and diversity in insular freshwater fish species. The endemic Betta species of the island have likely undergone distinct evolutionary trajectories due to the island&#x2019;s unique environmental conditions and geographic isolation. Producing genome assemblies for these taxa will address a significant knowledge gap and serve as a foundational step for future conservation genomics efforts in the region. This study aims to generate preliminary genome assemblies for three endemic 
                <italic toggle="yes">Betta</italic> species originating from Bangka, Indonesia, utilizing whole-genome sequencing methodologies.</p>
        </sec>
        <sec id="sec6">
            <title>Materials and methods</title>
            <sec id="sec7">
                <title>Ethics statement</title>
                <p>This study received ethical approval from the Ethics Commission for Animal Care and Use, National Research and Innovation Agency Republic of Indonesia (Approval No. 220/KE.02/SK/09/2024). All animal procedures followed institutional regulations and adhered to the ARRIVE 2.0 reporting guidelines, with the corresponding checklists available at 
                    <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.6084/m9.figshare.31136455">https://doi.org/10.6084/m9.figshare.31136455</ext-link>.
                    <sup>
                        <xref ref-type="bibr" rid="ref11">11</xref>
                    </sup>
                </p>
            </sec>
            <sec id="sec8">
                <title>Sample collection</title>
                <p>This study examines three endemic species of Betta: 
                    <italic toggle="yes">Betta burdigala</italic>, 
                    <italic toggle="yes">Betta chloropharynx</italic>, and 
                    <italic toggle="yes">Betta schalleri.</italic> The fish samples were collected from peatland water in South Bangka, Bangka Island, Indonesia. The map showing the origin locations of specimens on Bangka Island is presented in 
                    <xref ref-type="fig" rid="f1">
Figure 1</xref>. The males of 
                    <italic toggle="yes">B. schalleri</italic> and 
                    <italic toggle="yes">B. chlorpharynx</italic> have been found in Central Bangka (2&#x00b0;22'00.7"S 106&#x00b0;10'57.9"E) and 
                    <italic toggle="yes">B. burdigala</italic> has been found in South Bangka (2&#x00b0;50'24.8"S 106&#x00b0;26'12.7"E). The specimens were collected using a scope net with a mesh size of 0.5 mm as active gear. In-situ sampling data for morphometric and meristic analysis were obtained from three individuals each of 
                    <italic toggle="yes">B. schalerii</italic>, 
                    <italic toggle="yes">B. chloropharynx</italic>, and 
                    <italic toggle="yes">B. burdigala.</italic> The ten morphometric and seven meristic characters (Suppl Fig 1) based on Nur et al. (2022)
                    <sup>
                        <xref ref-type="bibr" rid="ref2">2</xref>
                    </sup> were measured using a digital caliper with an accurary 0.1 mm. The sampling design in this study used purposive sampling based on mature females or males with different shapes and colors. Males have longer ventral fins than females.
                    <sup>
                        <xref ref-type="bibr" rid="ref12">12</xref>
                    </sup> The males also have more vibrant and diverse body colors than females.
                    <sup>
                        <xref ref-type="bibr" rid="ref13">13</xref>
                    </sup> The morphometric and meristic data were analyzed descriptively.</p>
                <fig fig-type="figure" id="f1" orientation="portrait" position="float">
                    <label>
Figure 1. </label>
                    <caption>
                        <title>The specimen origin locations of 
                            <italic toggle="yes">Betta schalleri</italic> and 
                            <italic toggle="yes">Betta chloropharynx</italic> are found in ST.1 (Central Bangka), while 
                            <italic toggle="yes">Betta burdigala</italic> is found in ST.2 (South Bangka).</title>
                    </caption>
                    <graphic id="gr1" orientation="portrait" position="float" xlink:href="https://f1000research-files.f1000.com/manuscripts/192703/46f9c88e-2ba2-45ce-9e5b-a5affe1e3b0e_figure1.gif"/>
                </fig>
                <p>One male specimen from each Betta species was euthanized using the rapid chilling method, which involved transferring the fish to water maintained at approximately 2&#x00b0;C with crushed ice.
                    <sup>
                        <xref ref-type="bibr" rid="ref14">14</xref>
                    </sup> The fish was left in this condition for 20 minutes until opercular movement ceased. Subsequently, tissue samples were collected, fixed with absolute ethanol, and stored in cryotubes for whole genome sequencing at the Central Sequencing Laboratory, BRIN, Bogor, Indonesia.</p>
            </sec>
            <sec id="sec9">
                <title>Genomic DNA extraction and sequencing</title>
                <p>The extraction of genomic DNA was performed using the Applied Biosystem MagMax
                    <sup>TM</sup> DNA Multi-Sample 2.0 kit (Thermo Fisher Scientific; CAT. A36570) following the manufacturer&#x2019;s instructions. Twenty mg of fish tissue is used for genome DNA extraction material for all Betta specimens. The genome concentration from the extraction was checked using Nanodrop and Qubit. Genome concentration by Nanodrop value between 227.45-289 ng/&#x03bc;l and Qubit value between 89.4-91.6 (ng/&#x03bc;l). The genome quality was checked using gel agarose with TBE agarose concentration 1%. The genomic DNA was subsequently prepared for library construction using the Ligation Sequencing DNA V14 kit (Oxford Nanopore Technology; SQK-LSK114) in accordance with the manufacturer&#x2019;s instructions. Following this, the library was sequenced on a PromethION device utilizing PromethION Flow Cells Packs (Oxford Nanopore Technology; FLO-PRO114M). The sequencing parameters we employed included a run duration of 96 hours, a pre-scan interval of 1.5 hours, basecalling using the High-accuracy model at 400 bps, and a minimum Q score of 9. The sequencing software utilizes MinKNOW (25.03.7), Bream (8.4.4), configuration (6.4.10), basecalling Dorado (dna_r10.4.1_e8.2_400bps_
hac@4.3.0), and MinKNOW Core (6.4.8). The genome sequence data for 
                    <italic toggle="yes">Betta burdigala</italic> includes 16.38 million reads and 37.39 gigabases. For 
                    <italic toggle="yes">Betta chloropharynx</italic>, the data comprises 14.97 million reads and 57.97 gigabases. Meanwhile, 
                    <italic toggle="yes">Betta schalleri</italic> has 11.83 million reads and 23.75 gigabases.</p>
            </sec>
            <sec id="sec10">
                <title>Genome assembly and annotation</title>
                <p>The genome assembly and annotation described in this paper were conducted in accordance with the methodology performed by Imron et al.
                    <sup>
                        <xref ref-type="bibr" rid="ref15">15</xref>
                    </sup> Genome assembly estimation was done using Flye 2.9.5,
                    <sup>
                        <xref ref-type="bibr" rid="ref16">16</xref>
                    </sup> while genome scaffolding was conducted using RagTag 2.1.0
                    <sup>
                        <xref ref-type="bibr" rid="ref17">17</xref>
                    </sup> guided by genome reference of 
                    <italic toggle="yes">Betta splendens</italic> (GCF_900634795.4). Genome size estimation was conducted using Jellyfish software version 2.3.1
                    <sup>
                        <xref ref-type="bibr" rid="ref18">18</xref>
                    </sup> and was further processed using GenomeScope 2.0 v2.0.1. The assembly statistics were calculated using assembly stat version 1.0.1. The completeness of the assembly was estimated using Benchmarking Universal Single-Copy Orthologous (BUSCO) version 5.8.2, utilizing miniprot.
                    <sup>
                        <xref ref-type="bibr" rid="ref19">19</xref>&#x2013;
                        <xref ref-type="bibr" rid="ref21">21</xref>
                    </sup>
                </p>
                <p>Repetitive elements within the genome assembly were identified using RepeatModeler v2.0.6 in conjunction with RepeatMasker v4.1.7. (
                    <ext-link ext-link-type="uri" xlink:href="http://www.repeatmasker.org">http://www.repeatmasker.org</ext-link>). Prior to annotation, these repetitive regions were soft masked to minimize interference. Structural genome annotation encompassing gene prediction was conducted using the GALBA pipeline,
                    <sup>
                        <xref ref-type="bibr" rid="ref22">22</xref>
                    </sup> which employs miniprot
                    <sup>
                        <xref ref-type="bibr" rid="ref21">21</xref>
                    </sup> and AUGUSTUS,
                    <sup>
                        <xref ref-type="bibr" rid="ref23">23</xref>
                    </sup> integrating protein data from closely related species as extrinsic evidence. Specifically, protein data from 
                    <italic toggle="yes">Betta splendens</italic> (GCF_900634795.4), 
                    <italic toggle="yes">Anabas testudineus</italic> (GCF_900324465.2), and 
                    <italic toggle="yes">Channa argus</italic> (GCF_033026475.1) were utilized. Functional annotation of the resulting gene predictions was then performed using the &#x2018;funannotate annotate&#x2019; command from the Funannotate pipeline (
                    <ext-link ext-link-type="uri" xlink:href="https://funannotate.readthedocs.io/en/latest/install.html">https://funannotate.readthedocs.io/en/latest/install.html</ext-link>), incorporating tools such as InterProScan5,
                    <sup>
                        <xref ref-type="bibr" rid="ref24">24</xref>
                    </sup> Eggnog-Mapper,
                    <sup>
                        <xref ref-type="bibr" rid="ref25">25</xref>
                    </sup> and SignalP 5.0
                    <sup>
                        <xref ref-type="bibr" rid="ref26">26</xref>
                    </sup> to assign gene names and predict protein functions. Finally, the completeness of the genome annotation was evaluated using BUSCO v5.8.2.
                    <sup>
                        <xref ref-type="bibr" rid="ref20">20</xref>
                    </sup>
                </p>
            </sec>
            <sec id="sec11">
                <title>Duplicate genes classification and comparative genomics</title>
                <p>The protein sequences in each genomes were aligned to eachother using BLAST+ v. 2.14.1 (
                    <ext-link ext-link-type="uri" xlink:href="https://blast.ncbi.nlm.nih.gov/doc/blast-help/downloadblastdata.html">https://blast.ncbi.nlm.nih.gov/doc/blast-help/downloadblastdata.html</ext-link>). The alignment results and the gff (general feature format) file containing gene position in the genome were then further analyzed using the &#x2018;Duplicate_gene_classifier&#x2019; function of MCScanX
                    <sup>
                        <xref ref-type="bibr" rid="ref27">27</xref>
                    </sup> to identify gene duplications.</p>
                <p>We then performed all-against-all alignment of coding sequences (CDS) of three Betta genomes: using BLAST+ v. 2.14.1 (
                    <ext-link ext-link-type="uri" xlink:href="https://blast.ncbi.nlm.nih.gov/doc/blast-help/downloadblastdata.html">https://blast.ncbi.nlm.nih.gov/doc/blast-help/downloadblastdata.html</ext-link>). The alignment results were then concatenated into one file. The gff files were also concatenated. These files were then further analyzed using MCScanX
                    <sup>
                        <xref ref-type="bibr" rid="ref27">27</xref>
                    </sup> to detect gene synteny and collinearity. The results were then explored and visualize using SynVisio.
                    <sup>
                        <xref ref-type="bibr" rid="ref28">28</xref>
                    </sup>
                </p>
                <p>We also performed comparative analysis of Colony Stimulating Factor 1 Receptor A (CSF1RA), Melanocortin 1 Receptor (MC1R) and Paired Box 7 (PAX7) protein sequence among 
                    <italic toggle="yes">B. burdigala</italic>, 
                    <italic toggle="yes">B. chloropharynx</italic>, and 
                    <italic toggle="yes">B. schalleri</italic>, alongside 
                    <italic toggle="yes">B. splendens, Anabas testudineus, Channa argus, Oreochromis niloticus, Danio rerio, and Carassius auratus.</italic> The protein accession of CSF1RA that we used are: XP026135817.1, XP026135818.1, NP571747.1, XP021336731.1, XP003455234.1, XP013133007.1, XP067373776.1, XP067373775.1, XP026213579.1, XP055368253.1, XP055368253.1, and XP029020690.1. The protein accession of MC1R that we used are: NP_851301.1, XP_005159236.1, XP_026112973.1, XP_026112974.1, XP_005467175.1, XP_055363428.1, XP_067343026.1, XP_067343026.1, XP_026234205.1. The protein accession of PAX7 that we used are: XP_025763203.1, XP_005459058.1, XP_067361857.1, XP_029005486.1, XP_029005485.1, XP_026204402.1, XP_026204405.1, XP_025763202.1, XP_067361858.1, XP_026204404.1, XP_029005487.1, XP_026204403.1, NP_571407.2, NP_571400.1, XP_009304561.1, XP_026130952.1, XP_026130953.1. The protein sequence alignments were performed using Clustal Omega
                    <sup>
                        <xref ref-type="bibr" rid="ref29">29</xref>
                    </sup> via the European Bioinformatics Institute website (
                    <ext-link ext-link-type="uri" xlink:href="https://www.ebi.ac.uk/jdispatcher/msa/clustalo">https://www.ebi.ac.uk/jdispatcher/msa/clustalo</ext-link>). Subsequently, these alignments were used for phylogenetic reconstruction with IQ-TREE,
                    <sup>
                        <xref ref-type="bibr" rid="ref30">30</xref>
                    </sup> and the results were visualized using TreeViewer.
                    <sup>
                        <xref ref-type="bibr" rid="ref31">31</xref>
                    </sup>
                </p>
            </sec>
        </sec>
        <sec id="sec12" sec-type="results">
            <title>Results</title>
            <sec id="sec13">
                <title>Fish morphology</title>
                <p>The morphology photo of Betta spp. is presented in this research as shown in 
                    <xref ref-type="fig" rid="f2">
Figure 2</xref> for 
                    <italic toggle="yes">B. burdigala</italic> (A), 
                    <italic toggle="yes">B. chloropharynx</italic> (B), and 
                    <italic toggle="yes">B. schalleri</italic> (C). 
                    <xref ref-type="table" rid="T1">
Table 1</xref> outlines the meristic characteristics that distinguish them. The meristic and morphometric characters are presented in Suppl Fig 1.</p>
                <fig fig-type="figure" id="f2" orientation="portrait" position="float">
                    <label>
Figure 2. </label>
                    <caption>
                        <title>The morphology of 
                            <italic toggle="yes">B. burdigala</italic> (A), 
                            <italic toggle="yes">B. chloropharynx</italic> (B) and 
                            <italic toggle="yes">B. schalleri</italic> (C).</title>
                    </caption>
                    <graphic id="gr2" orientation="portrait" position="float" xlink:href="https://f1000research-files.f1000.com/manuscripts/192703/46f9c88e-2ba2-45ce-9e5b-a5affe1e3b0e_figure2.gif"/>
                </fig>
                <table-wrap id="T1" orientation="portrait" position="float">
                    <label>
Table 1. </label>
                    <caption>
                        <title>Meristic and morphometric character of 
                            <italic toggle="yes">B. burdigala, B. chloropharynx</italic>and and 
                            <italic toggle="yes">B. schalleri.</italic> The average of morphometric characters as a percentage to standard length with standard deviation.</title>
                    </caption>
                    <table content-type="article-table" frame="hsides">
                        <thead>
                            <tr>
                                <th align="left" colspan="1" rowspan="1" valign="top"/>
                                <th align="left" colspan="1" rowspan="1" valign="top">

                                    <italic toggle="yes">B. burdigala</italic>
</th>
                                <th align="left" colspan="1" rowspan="1" valign="top">

                                    <italic toggle="yes">B. chloropharynx</italic>
</th>
                                <th align="left" colspan="1" rowspan="1" valign="top">

                                    <italic toggle="yes">B. schalleri</italic>
</th>
                            </tr>
                        </thead>
                        <tbody>
                            <tr>
                                <td align="left" colspan="4" rowspan="1" valign="top">
                                    <bold>Meristic character</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Dorsal fin radii</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">D.I. 13&#x2013;14</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">D.I.8-9</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">D.I.8-9</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Anal fin radii</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">A.I&#x2013;II. 23&#x2013;24</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">A.I-II. 27-28</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">A.I-II.22-23</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Caudal radii</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">C.XV</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">C.XV</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">-</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Standard length (cm)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">2.46 &#x00b1; 0.13</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">9.95 &#x00b1; 0.91</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">5.21 &#x00b1; 1.23</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="4" rowspan="1" valign="top">
                                    <bold>Morphometric character</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Post-orbital length (%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">34.71 &#x00b1; 8.17</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">47.60 &#x00b1; 1.06</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">45.52 &#x00b1; 0.74</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Dorsal fin length (%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">30.43 &#x00b1; 1.68</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">14.00 &#x00b1; 0.29</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">15.01 &#x00b1; 0.95</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Predorsal length (%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">51.96 &#x00b1; 2.20</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">65.17 &#x00b1; 0.81</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">63.01 &#x00b1; 1.26</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Postdorsal length (%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">17.33 &#x00b1; 3.72</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">22.45 &#x00b1; 1.69</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">21.16 &#x00b1; 1.28</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Orbital diameter (%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">6.52 &#x00b1; 1.81</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">9.63 &#x00b1; 0.51</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">9.24 &#x00b1; 0.75</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Body depth (%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">20.48 &#x00b1; 1.28</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">25.78 &#x00b1; 1.68</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">27.59 &#x00b1; 0.25</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Head length (%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">29.04 &#x00b1; 0.60</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">33.97 &#x00b1; 1.40</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">34.90 &#x00b1; 1.90</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Anal fin length (%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">46.15 &#x00b1; 5.16</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">49.30 &#x00b1; 0.17</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">47.73 &#x00b1; 1.91</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Preanal length (%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">47.73 &#x00b1; 3.99</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">47.45 &#x00b1; 1.16</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">47.91 &#x00b1; 0.53</td>
                            </tr>
                        </tbody>
                    </table>
                </table-wrap>
            </sec>
            <sec id="sec14">
                <title>

                    <italic toggle="yes">Betta burdigala</italic>
</title>
                <p>

                    <italic toggle="yes">Betta burdigala</italic> is classified within the 
                    <italic toggle="yes">Betta coccina</italic> group.
                    <sup>
                        <xref ref-type="bibr" rid="ref32">32</xref>
                    </sup> This species is characterized by its red coloration and a size range of 2-3 cm, with distinct morphological features illustrated in 
                    <xref ref-type="fig" rid="f2">
Figure 2A</xref> that differentiate it from other species within the 
                    <italic toggle="yes">Betta coccina</italic> group. The meristic characteristics of 
                    <italic toggle="yes">B. burdigala</italic> are comprehensively presented in 
                    <xref ref-type="table" rid="T1">
Table 1</xref>. In comparison to 
                    <italic toggle="yes">B. uberis</italic>,
                    <sup>
                        <xref ref-type="bibr" rid="ref33">33</xref>
                    </sup> 
                    <italic toggle="yes">B. burdigala</italic> exhibits fewer dorsal fin rays (14-15 vs. 14-17), subdorsal scales (11-11.5 vs. 12-13.5), predorsal scales (15-16 vs. 18-20), and postdorsal scales (8 vs. 9-11). Regarding morphometric characteristics, 
                    <italic toggle="yes">B. burdigala</italic> demonstrates a longer postdorsal length as a percentage of standard length (12.19-20.85% vs. 13.5-17.8%), a shorter dorsal fin base (28.12-32.03% vs. 30.0-37.2%), and a greater postorbital length (23.20-41.36% vs. 13.4-16.8%).</p>
            </sec>
            <sec id="sec15">
                <title>

                    <italic toggle="yes">Betta chloropharynx</italic>
</title>
                <p>

                    <italic toggle="yes">Betta chloropharynx</italic>, depicted in 
                    <xref ref-type="fig" rid="f2">
Figure 2B</xref>, is a member of the 
                    <italic toggle="yes">Betta waseri</italic> group.
                    <sup>
                        <xref ref-type="bibr" rid="ref34">34</xref>
                    </sup> This group is distinguished by a unique pattern on the ventral side of the head. 
                    <italic toggle="yes">Betta chloropharynx</italic> can be differentiated from 
                    <italic toggle="yes">B. hipposideros</italic> by several characteristics: it possesses &#x03c9;-shaped black throat markings as opposed to horseshoe-shaped ones, lacks transverse lines on the caudal fin, and has fewer subdorsal scales, typically 5-6 compared to 6.5 (
                    <xref ref-type="table" rid="T1">
Table 1</xref>). In comparison to 
                    <italic toggle="yes">B. renata</italic>, 
                    <italic toggle="yes">B. chloropharynx</italic> exhibits &#x03c9;-shaped black throat marks instead of kidney-shaped ones, lacks transverse lines on the dorsal and caudal regions, has an unspotted operculum rather than a speckled one, and features a yellow underside on the operculum instead of a black edge, with fewer subdorsal scales, mode 5-6 versus 6.5. The distinctions between 
                    <italic toggle="yes">B. chloropharynx</italic> and 
                    <italic toggle="yes">B. spilotogena</italic> include &#x03c9;-shaped black throat marks versus a central black spot, an unspotted operculum versus a spotted one, and an operculum with a yellow underside versus a posterior edge.
                    <sup>
                        <xref ref-type="bibr" rid="ref35">35</xref>
                    </sup>
                </p>
            </sec>
            <sec id="sec16">
                <title>

                    <italic toggle="yes">Betta schalleri</italic>
</title>
                <p>In 
                    <xref ref-type="fig" rid="f2">
Figure 2C</xref>, 
                    <italic toggle="yes">Betta schalleri</italic>, when compared to other 
                    <italic toggle="yes">B. pugnax</italic>,
                    <sup>
                        <xref ref-type="bibr" rid="ref35">35</xref>
                    </sup> demonstrates distinct meristic characteristics. It possesses a greater number of anal fin rays (27 vs. 23-25), a higher count of dorsal fin rays than 
                    <italic toggle="yes">B. cracens</italic> and 
                    <italic toggle="yes">B. fusca</italic> (10-11 vs. 8-9), more subdorsal scales than 
                    <italic toggle="yes">B. cracens</italic> and 
                    <italic toggle="yes">B. fusca</italic> (6.5-7 vs. 5.5-6), a greater number of lateral scales than 
                    <italic toggle="yes">B. fusca</italic> (31 vs. 29), fewer lateral scales than 
                    <italic toggle="yes">B. cracens</italic> (31 vs. 32-33), and a reduced number of predorsal scales compared to 
                    <italic toggle="yes">B. cracens, B. fusca,
</italic> and 
                    <italic toggle="yes">B. raja</italic> (17-19 vs. 20-24). In term of morphometric characteristics (expressed as a percentage of standard length; 
                    <xref ref-type="table" rid="T1">
Table 1</xref>), 
                    <italic toggle="yes">B. schalleri</italic> exhibits a longer head length compared to 
                    <italic toggle="yes">B. pugnax</italic>, 
                    <italic toggle="yes">B. cracens,
</italic> and 
                    <italic toggle="yes">B. fusca</italic> (35.5-36.5% vs. 27.5-35.2%), a shorter predorsal length compared to 
                    <italic toggle="yes">B. fusca</italic> (62.7-66.3% vs. 68.5-70.2%), a longer preanal length compared to 
                    <italic toggle="yes">B. cracens</italic> (47.16-48.30 % vs. 42.0-46.1%), a greater body depth compared to 
                    <italic toggle="yes">B. cracens</italic> (27.38-27.93 % vs. 21.2-24.2%), an extended dorsal fin base compared to 
                    <italic toggle="yes">B. cracens</italic> (14.11-16.32% vs. 10.5-11.6%), and a shorter anal fin base compared to 
                    <italic toggle="yes">B. cracens</italic> (45.49-50.16 % vs. 53.4-55.7%).</p>
            </sec>
            <sec id="sec17">
                <title>Genome assembly</title>
                <p>The genome assemblies of 
                    <italic toggle="yes">B. burdigala</italic>, 
                    <italic toggle="yes">B. schalleri</italic>, and 
                    <italic toggle="yes">B. chloropharynx</italic> demonstrated high contiguity and completeness, with 
                    <italic toggle="yes">B. chloropharynx</italic> showing the strongest contiguity, while 
                    <italic toggle="yes">B. burdigala</italic> and 
                    <italic toggle="yes">B. schalleri</italic> also provide high-quality genomic resources suitable for comparative and evolutionary studies (
                    <xref ref-type="fig" rid="f3">
Figure 3</xref>). The genome assembly of 
                    <italic toggle="yes">B. burdigala</italic> totaled ~422 Mbp across 4,868 scaffolds and 6,904 contigs, with a scaffold N50 of 18 Mb and the longest scaffold reaching 33.2 Mb. The assembly was highly complete, with a BUSCO score of 99.1% (98.6% single-copy, 0.5% duplicated), while the GC content was 45.2% and gaps accounted for only 0.048%. The 
                    <italic toggle="yes">B. chloropharynx</italic> genome was slightly larger at ~474 Mbp, assembled into 3,273 scaffolds and 4,918 contigs. It showed the greatest contiguity, with a scaffold N50 of 20 Mbp, a maximum scaffold length of 35.9 Mbp, and the highest mean scaffold length (~145 kb). BUSCO completeness reached 99.3% (98.7% single-copy, 0.6% duplicated), the highest among the three species, with minimal fragmentation (0.5%) and missing genes (0.2%). The 
                    <italic toggle="yes">Betta schalleri</italic> assembly spanned ~433 Mbp with 8,474 scaffolds and 10,762 contigs, reflecting greater fragmentation. The scaffold N50 was 19 Mb, with the longest scaffold at 34.7 Mbp and a mean length of ~51 kb. BUSCO assessment indicated 99.1% completeness (98.8% single-copy, 0.4% duplicated), with GC content at 44.8% and low gap content (0.053%).</p>
                <fig fig-type="figure" id="f3" orientation="portrait" position="float">
                    <label>
Figure 3. </label>
                    <caption>
                        <title>Main features of the genome assemblies of 
                            <italic toggle="yes">Betta burdigala</italic>, 
                            <italic toggle="yes">Betta chloropharynx,
</italic> and 
                            <italic toggle="yes">Betta schalleri.</italic>
</title>
                    </caption>
                    <graphic id="gr3" orientation="portrait" position="float" xlink:href="https://f1000research-files.f1000.com/manuscripts/192703/46f9c88e-2ba2-45ce-9e5b-a5affe1e3b0e_figure3.gif"/>
                </fig>
            </sec>
            <sec id="sec18">
                <title>Genome annotation</title>
                <p>Repeats annotation</p>
                <p>Annotation of repetitive elements in the genomes of 
                    <italic toggle="yes">B. burdigala</italic>, 
                    <italic toggle="yes">B. chloropharynx</italic>, and 
                    <italic toggle="yes">B. schalleri</italic> revealed that transposable elements (TEs) comprise a substantial portion of each genome, with notable variation in both content and composition among species (
                    <xref ref-type="table" rid="T2">
Table 2</xref>). Retroelements were a dominant repeat category, accounting for 11.3% in BBS, 11.4% in 
                    <italic toggle="yes">B. burdigala</italic>, and up to 15.9% in 
                    <italic toggle="yes">B. chloropharynx.</italic> Among these, LINEs were the most prevalent, particularly the L2/CR1/Rex and L1/CIN4 subfamilies, followed by LTR elements such as Gypsy/DIRS1 and BEL/Pao, which collectively contributed to the structural and regulatory diversification of the genome. Although SINEs and Penelope elements were detected, they represented only a minor fraction of the total retroelement content (&lt;0.3%).</p>
                <table-wrap id="T2" orientation="portrait" position="float">
                    <label>
Table 2. </label>
                    <caption>
                        <title>Classification of repeat elements of 
                            <italic toggle="yes">B. burdigala</italic>, 
                            <italic toggle="yes">B. chloropharynx</italic>, and 
                            <italic toggle="yes">B. schalleri</italic> genome assemblies.</title>
                    </caption>
                    <table content-type="article-table" frame="hsides">
                        <thead>
                            <tr>
                                <th align="left" colspan="1" rowspan="2" valign="top">Repeat category</th>
                                <th align="left" colspan="3" rowspan="1" valign="top">Percentage of sequence (%)</th>
                            </tr>
                            <tr>
                                <th align="left" colspan="1" rowspan="1" valign="top">

                                    <italic toggle="yes">Betta burdigala</italic>
</th>
                                <th align="left" colspan="1" rowspan="1" valign="top">

                                    <italic toggle="yes">Betta chloropharynx</italic>
</th>
                                <th align="left" colspan="1" rowspan="1" valign="top">

                                    <italic toggle="yes">Betta schalleri</italic>
</th>
                            </tr>
                        </thead>
                        <tbody>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Retroelements</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>5.98</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>8.39</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>6.18</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">SINEs</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.21</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.42</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.39</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Penelope</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.03</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.01</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.32</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">LINEs</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">4.03</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">5.24</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">3.53</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">CRE/SLACS</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">L2/CR1/Rex</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">2.53</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">3.31</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">2.22</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">R1/LOA/Jockey</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.17</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.24</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.11</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">R2/R4/NeSL</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.25</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.37</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.36</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">RTE/Bov-B
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.41</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.8</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.54</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">L1/CIN4</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.58</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.35</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.16</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">BEL/Pao</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.11</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.25</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.21</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Ty1/Copia</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.01</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.02</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.03</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Gypsy/DIRS1</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.97</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.53</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.14</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Retroviral</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.43</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.65</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.32</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">DNA transposons</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>3.85</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>5.54</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>4.02</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">hobo-Activator
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.18</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.86</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.5</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Tc1-IS630-Pogo</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.68</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.65</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.08</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">En-Spm
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">MULE-MuDR
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">PiggyBac</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.13</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.2</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.1</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Tourist/Harbinger</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.62</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.53</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">0.32</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Rolling-circles
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.04</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.19</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.03</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Unclassified</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>4.21</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>5.93</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>3.94</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Total Interspersed</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>14.03</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>19.86</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>14.14</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Small RNA</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.12</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.34</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.25</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Satellites</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.06</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.07</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.05</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Simple repeats</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>2.14</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>1.59</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>1.82</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Low complexity</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.23</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.21</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>0.22</bold>
</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Total Masked Bases</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>16.54</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>22.08</bold>
</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">
                                    <bold>16.30</bold>
</td>
                            </tr>
                        </tbody>
                    </table>
                </table-wrap>
                <p>DNA transposons were the second most abundant repeat class, comprising 6.5%, 9.8%, and 7.0% of the genomes of 
                    <italic toggle="yes">B. burdigala</italic>, 
                    <italic toggle="yes">B. chloropharynx</italic>, and 
                    <italic toggle="yes">B. schalleri</italic>, respectively (
                    <xref ref-type="table" rid="T2">
Table 2</xref>). The dominant families within this group included hobo-Activator, Tc1-IS630-Pogo, and En-Spm elements. These transposons are known for their cut-and-paste mechanism, and their relative abundance suggests that DNA-mediated transposition has played an important role in shaping genome architecture, particularly in BBC where their proportion was the highest. Interestingly, MULE-MuDR and PiggyBac elements were detected at low levels or were absent, suggesting potential lineage-specific losses or underrepresentation due to assembly or annotation limitations.</p>
                <p>In addition to classified repeat categories, a significant fraction of the genome (3.9&#x2013;5.9%) consisted of unclassified elements, indicating the presence of either novel transposable elements or highly diverged copies that defy current classification models (
                    <xref ref-type="table" rid="T2">
Table 2</xref>). Moreover, 22&#x2013;30% of repetitive content across the three genomes fell into the &#x201c;Other&#x201d; category, representing repeat families that could not be assigned confidently to standard classifications. The higher repeat content observed in 
                    <italic toggle="yes">B. chloropharynx</italic>, particularly in retrotransposons and unclassified repeats, may reflect recent TE amplification events or reduced efficacy of TE suppression mechanisms in this lineage.</p>
                <p>Structural and functional annotation and gene duplication analysis</p>
                <p>The genome annotation summary across the three Betta species&#x2014;
                    <italic toggle="yes">B. burdigala</italic>, 
                    <italic toggle="yes">B. chloropharynx</italic>, and 
                    <italic toggle="yes">B. schalleri</italic>&#x2014;revealed a broadly similar genomic architecture, with minor differences in gene structure metrics (
                    <xref ref-type="table" rid="T3">
Table 3</xref>). All three species exhibit approximately 1.3 transcripts per gene on average, and the number of predicted transcripts ranged from 31,517 in 
                    <italic toggle="yes">B. burdigala</italic> to 32,786 in 
                    <italic toggle="yes">B. chloropharynx.</italic> The mean exon size was consistent (172&#x2013;174 bp), while the mean gene locus size ranged from 8,784 bp in 
                    <italic toggle="yes">B. burdigala</italic> to 9,013 bp in 
                    <italic toggle="yes">B. chloropharynx.</italic> Notably, the percentage of genes with alternative transcript variants was relatively stable across species (~23%), and most genes were multi-exonic (over 91%), indicating conserved splicing complexity in the genus.</p>
                <table-wrap id="T3" orientation="portrait" position="float">
                    <label>
Table 3. </label>
                    <caption>
                        <title>Genome annotation summary for the genome assembly of 
                            <italic toggle="yes">Betta burdigala</italic>, 
                            <italic toggle="yes">Betta chloropharynx</italic>, and 
                            <italic toggle="yes">Betta schalleri.</italic>
</title>
                    </caption>
                    <table content-type="article-table" frame="hsides">
                        <thead>
                            <tr>
                                <th align="left" colspan="1" rowspan="1" valign="top">Statistic</th>
                                <th align="left" colspan="1" rowspan="1" valign="top">Betta burdigala 
(BBB)</th>
                                <th align="left" colspan="1" rowspan="1" valign="top">Betta chloropharynx 
(BBC)</th>
                                <th align="left" colspan="1" rowspan="1" valign="top">
Betta schalleri 
(BBS)</th>
                            </tr>
                        </thead>
                        <tbody>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Max transcripts/gene</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">12</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">11</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">11</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Mean exon size (bp)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">173.2</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">174.1</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">172.7</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Mean gene locus size (bp)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">8784.6</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">9013.1</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">8942.5</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Mean distinct exons/gene</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">10.4</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">10.2</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">10.4</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Mean transcripts/gene</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.3</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.3</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1.3</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Mean transcript size (bp)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">2013.8</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1995.4</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">2016.1</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Number of distinct exons</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">245812</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">251941</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">247092</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Number of genes</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">23645</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">24597</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">23767</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Genes with alt. transcripts</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">5,440 (23.0%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">5,615 (22.8%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">5,479 (23.1%)</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Multi-exon genes</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">21,835 (92.3%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">22,592 (91.8%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">21,922 (92.2%)</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Predicted transcripts</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">31517</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">32786</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">31694</td>
                            </tr>
                            <tr>
                                <td align="left" colspan="1" rowspan="1" valign="top">Single-exon genes</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1,810 (7.7%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">2,005 (8.2%)</td>
                                <td align="left" colspan="1" rowspan="1" valign="top">1,845 (7.8%)</td>
                            </tr>
                        </tbody>
                    </table>
                </table-wrap>
                <p>Regarding genome composition, the GC content of genes and introns was consistent across species at 46% and 44%, respectively (
                    <xref ref-type="fig" rid="f4">
Figure 4A</xref>). Exonic GC content was slightly higher, ranging from 54% in 
                    <italic toggle="yes">B. chloropharynx</italic> and 
                    <italic toggle="yes">B. schalleri</italic> to 55% in 
                    <italic toggle="yes">B. burdigala</italic> (
                    <xref ref-type="fig" rid="f4">
Figure 4B</xref>). Exons accounted for 9&#x2013;10% of the genome, while genes (including exons and introns) occupied approximately 47&#x2013;49% (
                    <xref ref-type="fig" rid="f4">
Figure 4B</xref>). Introns alone contributed 38&#x2013;40% of the genome, reflecting their substantial role in genome size and structure (
                    <xref ref-type="fig" rid="f4">
Figure 4B</xref>). These values suggest that, despite minor quantitative differences, the overall organization and composition of the genomes are highly conserved across the Betta species analyzed.</p>
                <fig fig-type="figure" id="f4" orientation="portrait" position="float">
                    <label>
Figure 4. </label>
                    <caption>
                        <title>Genome annotation statistics and assessment of 
                            <italic toggle="yes">Betta burdigala</italic>, 
                            <italic toggle="yes">Betta chloropharynx</italic>, and 
                            <italic toggle="yes">Betta schalleri.</italic>
</title>
                        <p>(A) GC content by component of the three betta species genome assemblies. (B) Genome composition by component of the three Betta species genome assemblies. (C) BUSCO assessment of genome annotation results for the three Betta species genome assemblies. (D) Gene duplication classification in the genome of the three Betta species. Note that a gene can be classified into more than one gene duplication type.</p>
                    </caption>
                    <graphic id="gr4" orientation="portrait" position="float" xlink:href="https://f1000research-files.f1000.com/manuscripts/192703/46f9c88e-2ba2-45ce-9e5b-a5affe1e3b0e_figure4.gif"/>
                </fig>
                <p>The BUSCO analysis using the 
                    <italic toggle="yes">actinopterygii_odb10</italic> dataset revealed high completeness across all three 
                    <italic toggle="yes">Betta</italic> species proteomes, indicating high-quality gene annotations (
                    <xref ref-type="fig" rid="f4">
Figure 4C</xref>). 
                    <italic toggle="yes">Betta burdigala</italic> showed the highest completeness with 98.0% of BUSCOs identified as complete, closely followed by 
                    <italic toggle="yes">B. schalleri</italic> at 97.9%, and 
                    <italic toggle="yes">B. chloropharynx</italic> at 97.8%. The majority of these complete BUSCOs were single-copy, representing 78.5&#x2013;78.8% of the total, while duplicated BUSCOs accounted for approximately 19.2&#x2013;19.3%, suggesting some level of gene duplication across all three genomes.</p>
                <p>We also explored the gene duplication patterns revealing notable similarities and subtle differences in the distribution of duplication types among the three 
                    <italic toggle="yes">Betta</italic> species (
                    <xref ref-type="fig" rid="f4">
Figure 4D</xref>). Across all species, dispersed duplications were the most prevalent, with 
                    <italic toggle="yes">B. chloropharynx</italic> showing the highest count (15,831 genes), followed closely by 
                    <italic toggle="yes">B. schalleri</italic> (15,269 genes) and 
                    <italic toggle="yes">B. burdigala</italic> (15,157 genes). This suggests that dispersed duplications represent a dominant mechanism contributing to gene expansion in these genomes, likely reflecting ongoing evolutionary pressures and functional diversification.</p>
                <p>Other duplication categories, including tandem, proximal, and whole-genome duplication (WGD)/segmental events, were represented in roughly similar proportions across species (
                    <xref ref-type="fig" rid="f6">
Figure 6</xref>). Tandem duplicates ranged from 2,277 in 
                    <italic toggle="yes">B. schalleri</italic> to 2,437 in 
                    <italic toggle="yes">B. chloropharynx</italic>, while proximal duplications were more variable, with 
                    <italic toggle="yes">B. schalleri</italic> showing the lowest count (673) compared to 924 in 
                    <italic toggle="yes">B. chloropharynx.</italic> WGD or segmental duplicates remained relatively consistent across species (approximately 2,270&#x2013;2,370), highlighting a shared genomic history of large-scale duplication events. Singleton genes, which lack detectable paralogs, accounted for 3,114&#x2013;3,178 genes depending on the species.</p>
            </sec>
            <sec id="sec19">
                <title>Comparative genomic</title>
                <p>We conducted a collinearity analysis to investigate genome-level relationships among 
                    <italic toggle="yes">B. burdigala</italic>, 
                    <italic toggle="yes">B. chloropharynx</italic>, and 
                    <italic toggle="yes">B. schalleri.</italic> The analysis identified conserved syntenic gene blocks between each pair of species, which were subsequently quantified as collinear gene pairs (
                    <xref ref-type="fig" rid="f5">
Figure 5A</xref>). A total of 16,948 pairs were detected between 
                    <italic toggle="yes">B. burdigala</italic> and 
                    <italic toggle="yes">B. chloropharynx</italic> (33.15%), 16,778 pairs between 
                    <italic toggle="yes">B. burdigala</italic> and 
                    <italic toggle="yes">B. schalleri</italic> (32.81%), and 17,405 pairs between 
                    <italic toggle="yes">B. chloropharynx</italic> and 
                    <italic toggle="yes">B. schalleri</italic> (34.04%). These values indicate a high degree of genome conservation across all three species, with each pair retaining roughly one-third of the total detected collinear relationships.</p>
                <fig fig-type="figure" id="f5" orientation="portrait" position="float">
                    <label>
Figure 5. </label>
                    <caption>
                        <title>Collinearity analysis of genome assembly of 
                            <italic toggle="yes">Betta burdigala</italic> (BBur), 
                            <italic toggle="yes">Betta schalleri</italic> (BSch), and 
                            <italic toggle="yes">Betta chloropharynx</italic> (BChl).</title>
                        <p>(A) syntenic block connection of the three genomes. (B) Pairwise collinearity among Betta species. (C) Pylogenetic tree based on synteny.</p>
                    </caption>
                    <graphic id="gr5" orientation="portrait" position="float" xlink:href="https://f1000research-files.f1000.com/manuscripts/192703/46f9c88e-2ba2-45ce-9e5b-a5affe1e3b0e_figure5.gif"/>
                </fig>
                <p>Among the three comparisons, the highest level of collinearity was observed between 
                    <italic toggle="yes">B. chloropharynx</italic> and 
                    <italic toggle="yes">B. schalleri</italic>, suggesting that these two species are slightly more closely related to each other than to 
                    <italic toggle="yes">B. burdigala</italic> (
                    <xref ref-type="fig" rid="f5">
Figure 5B</xref>). In contrast, 
                    <italic toggle="yes">B. burdigala</italic> shows a similar but marginally lower level of collinearity with both 
                    <italic toggle="yes">B. chloropharynx</italic> and 
                    <italic toggle="yes">B. schalleri</italic>, implying that 
                    <italic toggle="yes">B. burdigala</italic> likely diverged earlier from the lineage leading to 
                    <italic toggle="yes">B. chloropharynx</italic> and 
                    <italic toggle="yes">B. schalleri.</italic> Visualization of the results using a dendrogram and a network graph further supports this interpretation. The dendrogram places 
                    <italic toggle="yes">B. chloropharynx</italic> and 
                    <italic toggle="yes">B. schalleri</italic> as sister species, with 
                    <italic toggle="yes">B. burdigala</italic> forming an outgroup (
                    <xref ref-type="fig" rid="f5">
Figure 5C</xref>). The network graph illustrates strong syntenic connections among all three species, but with the thickest edge linking 
                    <italic toggle="yes">B. chloropharynx</italic> and 
                    <italic toggle="yes">B. schalleri</italic>, reflecting their higher degree of shared genome organization.</p>
                <p>We also did comparative analysis of three genes that might involve in color patterning of fishes which are Colony Stimulating Factor 1 Receptor A (CSF1RA), Melanocortin 1 Receptor (MC1R) and Paired Box 7 (PAX7). The protein sequence alignment are available in supplementary files (Supplementary file 1, Supplementary file 2, and Supplementary file 3). We found that the CSF1RA phylogenetic tree closely resembles the phylogenetic tree of the nine fish species compared based on NCBI taxonomic data (
                    <xref ref-type="fig" rid="f6">
Figure 6A and D</xref>). On the other hand, we observed that the branching pattern of the MC1R and PAX7 phylogenetic tree does not align with the species phylogenetic tree (Suppl Fig 2). We also identified two significant protein insertions in the CSF1RA of 
                    <italic toggle="yes">B. burdigala</italic> (
                    <xref ref-type="fig" rid="f6">
Figure 6B and C</xref>). The first insertion, consisting of 27 amino acids, is located at approximately alignment position 594, just before the start of the Kinase Domain (GKVLGAGAFG&#x2026;). The second insertion, comprising 28 amino acids, is situated at around alignment position 701, between the two lobes of the kinase domain.</p>
                <fig fig-type="figure" id="f6" orientation="portrait" position="float">
                    <label>
Figure 6. </label>
                    <caption>
                        <title>A comparative analysis of the Colony Stimulating Factor 1 Receptor A (CSF1RA) protein sequence among 
                            <italic toggle="yes">B. burdigala</italic>, 
                            <italic toggle="yes">B. chloropharynx</italic>, and 
                            <italic toggle="yes">B. schalleri</italic>, alongside 
                            <italic toggle="yes">B. splendens</italic>, 
                            <italic toggle="yes">Anabas testudineus</italic>, 
                            <italic toggle="yes">Channa argus, Oreochromis niloticus, Danio rerio, and Carassius auratus.</italic>
</title>
                        <p>(A) A phylogenetic tree derived from CSFRA protein alignments across nine fish species. (B) Multiple Sequence Alignment of the CSFRA protein in these nine fish species. (C) A zoomed-in view of the sequence alignment within the red line box in (B). (D) a phylogenetic tree of nine fish species based on NCBI taxonomic data. The complete protein sequence alignment of CSF1RA is available in Supplementary file 1.</p>
                    </caption>
                    <graphic id="gr6" orientation="portrait" position="float" xlink:href="https://f1000research-files.f1000.com/manuscripts/192703/46f9c88e-2ba2-45ce-9e5b-a5affe1e3b0e_figure6.gif"/>
                </fig>
            </sec>
        </sec>
        <sec id="sec20" sec-type="discussion">
            <title>Discussion</title>
            <p>Our study integrates meristic analyses and genome assemblies to provide a comparative framework for understanding divergence among three endemic 
                <italic toggle="yes">Betta</italic> species from Bangka Island: 
                <italic toggle="yes">B. burdigala</italic>, 
                <italic toggle="yes">B. chloropharynx</italic>, and 
                <italic toggle="yes">B. schalleri.</italic> Morphological comparisons revealed clear diagnostic traits that distinguish these species and align with their current taxonomic placement. 
                <italic toggle="yes">B. burdigala</italic> showed reductions in dorsal and predorsal scale counts, consistent with its placement in the 
                <italic toggle="yes">coccina</italic> group.
                <sup>
                    <xref ref-type="bibr" rid="ref32">32</xref>
                </sup> 
                <italic toggle="yes">B. chloropharynx</italic> was distinguished by its characteristic throat markings and opercular coloration typical of the 
                <italic toggle="yes">waseri</italic> group,
                <sup>
                    <xref ref-type="bibr" rid="ref34">34</xref>
                </sup> while 
                <italic toggle="yes">B. schalleri</italic> exhibited greater fin ray counts and deeper body proportions, traits associated with the 
                <italic toggle="yes">pugnax</italic> group.
                <sup>
                    <xref ref-type="bibr" rid="ref35">35</xref>
                </sup> These meristic patterns reinforce species boundaries and highlight morphological divergence even within closely related taxa.</p>
            <p>The genomic assemblies presented here represent the first references for these Bangka endemics. All three species demonstrated high contiguity and completeness, confirming their reliability for downstream analyses. Subtle genomic differences were also evident. 
                <italic toggle="yes">B. chloropharynx</italic> displayed the largest genome size, highest scaffold N50, and elevated retrotransposon content, suggesting lineage-specific repeat dynamics. Gene duplication profiles showed dispersed duplications as the dominant category across all species, while variation in tandem and proximal duplications may indicate lineage-specific expansions.
                <sup>
                    <xref ref-type="bibr" rid="ref36">36</xref>&#x2013;
                    <xref ref-type="bibr" rid="ref38">38</xref>
                </sup>
            </p>
            <p>These findings demonstrate that while overall genome organization and gene content remain conserved across the three species, lineage-specific signatures of divergence are detectable. The combination of high collinearity and subtle differences in repeat content and duplication patterns provides a genomic basis for understanding evolutionary relationships within the genus.
                <sup>
                    <xref ref-type="bibr" rid="ref39">39</xref>,
                    <xref ref-type="bibr" rid="ref40">40</xref>
                </sup> Moreover, the integration of meristic and genomic evidence strengthens taxonomic resolution, particularly in lineages where morphology alone may be insufficient.</p>
            <p>Together, the annotation and composition data indicate a strong conservation of gene architecture and genomic content within the Betta genus, consistent with their relatively recent divergence. Subtle differences, such as the slightly higher transcript count or gene locus size in 
                <italic toggle="yes">B. chloropharynx</italic>, may hint at ongoing lineage-specific regulatory or structural adaptations.
                <sup>
                    <xref ref-type="bibr" rid="ref41">41</xref>,
                    <xref ref-type="bibr" rid="ref42">42</xref>
                </sup> The consistent duplication profiles across the three species suggest conserved duplication dynamics within the Betta genus. However, the modest variation in tandem and proximal duplication counts may point to lineage-specific gene family expansions or contraction events, potentially linked to ecological adaptations or evolutionary divergence.
                <sup>
                    <xref ref-type="bibr" rid="ref37">37</xref>,
                    <xref ref-type="bibr" rid="ref43">43</xref>
                </sup>
            </p>
            <p>Collinearity analysis has demonstrated significant genome conservation, with 
                <italic toggle="yes">B. chloropharynx</italic> and 
                <italic toggle="yes">B. schalleri</italic> exhibiting the highest degree of synteny, thereby supporting their closer evolutionary relationship compared to 
                <italic toggle="yes">B. burdigala.</italic> These results further indicate that, although all three Betta species possess largely conserved genome architectures, 
                <italic toggle="yes">B. chloropharynx</italic> and 
                <italic toggle="yes">B. schalleri</italic> share the closest evolutionary relationship, with 
                <italic toggle="yes">B. burdigala</italic> diverging earlier. This underscores the effectiveness of collinearity analysis in elucidating fine-scale relationships among recently diverged species and provides a genomic framework for further comparative and evolutionary investigations within the Betta genus.
                <sup>
                    <xref ref-type="bibr" rid="ref41">41</xref>,
                    <xref ref-type="bibr" rid="ref44">44</xref>,
                    <xref ref-type="bibr" rid="ref45">45</xref>
                </sup> The observed genomic collinearity, particularly between 
                <italic toggle="yes">B. chloropharynx</italic> and 
                <italic toggle="yes">B. schalleri</italic>, aligns with findings in other fish taxa, where conserved synteny is common among closely related species despite independent chromosomal fusions or rearrangements in more distant lineages.
                <sup>
                    <xref ref-type="bibr" rid="ref46">46</xref>,
                    <xref ref-type="bibr" rid="ref47">47</xref>
                </sup>
            </p>
            <p>Our comparative genomic analysis reveals a two-layered evolutionary dynamic underlying pigmentation diversity in Betta species: strong conservation of core pigment-cell survival pathways alongside rapid divergence in genes governing color type and pattern formation. CSF1RA, a key regulator of melanophore and color pigments (xanthophores, erythrophores, and iridophore) development,
                <sup>
                    <xref ref-type="bibr" rid="ref48">48</xref>&#x2013;
                    <xref ref-type="bibr" rid="ref50">50</xref>
                </sup> follows the expected species phylogeny and shows high sequence conservation across all examined fishes, reflecting strong purifying selection on this essential signaling pathway. Notably, however, 
                <italic toggle="yes">B. burdigala</italic> exhibits two large amino-acid insertions positioned adjacent to and within the kinase domain, indicating species-specific modulation rather than disruption of receptor function. While further research is necessary, such structural changes might fine-tune the color pigment pattern and density, potentially enhancing this species&#x2019; vibrant coloration. In contrast, genes associated with pigment-cell fate and color intensity&#x2014;particularly PAX7 and MC1R&#x2014;show phylogenetic patterns that deviate from the species tree, implying accelerated evolution or lineage-specific selection. Divergence in PAX7, a major regulator of xanthophore and erythrophore lineages,
                <sup>
                    <xref ref-type="bibr" rid="ref51">51</xref>&#x2013;
                    <xref ref-type="bibr" rid="ref53">53</xref>
                </sup> is consistent with adaptive shifts affecting red&#x2013;yellow pigmentation, especially relevant given the pronounced red coloration in 
                <italic toggle="yes">B. burdigala.</italic> Similarly, the non-concordant evolution of MC1R, despite its variable role in teleost pigmentation,
                <sup>
                    <xref ref-type="bibr" rid="ref54">54</xref>&#x2013;
                    <xref ref-type="bibr" rid="ref56">56</xref>
                </sup> suggests relaxed constraint or functional innovation within the Betta lineage. Together, these findings indicate that Betta color diversity arises from conserved developmental frameworks overlaid by rapid gene-specific evolution and structural innovation, enabling fine-scale modulation of pigment cell types and color intensity across species.
                <sup>
                    <xref ref-type="bibr" rid="ref57">57</xref>
                </sup>
            </p>
            <p>Although our data do not directly address ecological or paleogeographic processes, previous studies suggest that the high endemism of Bangka&#x2019;s 
                <italic toggle="yes">Betta</italic> species has been shaped by Pleistocene paleogeography and the persistence of specialized peat swamp habitats.
                <sup>
                    <xref ref-type="bibr" rid="ref6">6</xref>,
                    <xref ref-type="bibr" rid="ref58">58</xref>&#x2013;
                    <xref ref-type="bibr" rid="ref63">63</xref>
                </sup> In this context, the divergence patterns we observed in both morphology and genomics are consistent with scenarios of historical geographic isolation and ecological filtering proposed by earlier work. Our results therefore provide the genetic and morphological evidence that complements these broader biogeographic hypotheses. These data not only support species delimitation and phylogenomic placement within the 
                <italic toggle="yes">Betta</italic> genus but also establish a foundation for future work linking genomic variation with ecology, adaptation, and conservation. Given the conservation status of these taxa, the genomic resources generated here are valuable for monitoring genetic diversity and informing management strategies for Bangka&#x2019;s unique freshwater biodiversity.</p>
        </sec>
        <sec id="sec21" sec-type="conclusion">
            <title>Conclusion</title>
            <p>This study provides the first integrated meristic and genomic comparison of three endemic Betta species from Bangka Island&#x2014;
                <italic toggle="yes">B. burdigala</italic>, 
                <italic toggle="yes">B. chloropharynx</italic>, and 
                <italic toggle="yes">B. schalleri.</italic> Meristic analyses confirmed diagnostic traits supporting their taxonomic distinction, while high-quality genome assemblies with near-complete BUSCO scores (&gt;97%) offer reliable references for evolutionary and conservation studies. Although overall genomic architecture is conserved, subtle differences in genome size, repeat composition, and duplication profiles highlight lineage-specific divergence, with synteny analyses indicating a closer relationship between 
                <italic toggle="yes">B. chloropharynx</italic> and 
                <italic toggle="yes">B. schalleri.</italic> By combining morphological and genomic evidence, this study not only strengthens the resolution of species boundaries but also establishes essential resources for monitoring genetic diversity and informing conservation strategies for these endangered freshwater fishes.</p>
        </sec>
    </body>
    <back>
        <sec id="sec24" sec-type="data-availability">
            <title>Data availability</title>
            <p>The data related to this project have been deposited under NCBI BioProject Accession PRJNA1328177 and are publicly available. The biosample accession numbers are SAMN51307167, SAMN51307168, and SAMN51307169 for 
                <italic toggle="yes">B. burdigala</italic>, 
                <italic toggle="yes">B. schalleri</italic>, and 
                <italic toggle="yes">B. chloropharynx</italic> respectively. The raw genome sequence reads have been deposited in the NCBI Sequence Read Archive (SRA) under the accession numbers SRR35652347 for 
                <italic toggle="yes">B. burdigala</italic>, SRR35653255 for 
                <italic toggle="yes">B. schalleri</italic>, and SRR35728893 and SRR35728892 for 
                <italic toggle="yes">B. chloropharynx.</italic> Additionally, the genome assemblies have been deposited in the NCBI GenBank database with accession numbers GCA_054471155.1, GCA_054471145.1, GCA_054471135.1 for 
                <italic toggle="yes">B. burdigala</italic>, 
                <italic toggle="yes">B. schalleri</italic>, and 
                <italic toggle="yes">B. chloropharynx</italic>, respectively.</p>
            <p>The genome assemblies and their annotations have also been deposited and are available in the National Scientific Repository of the National Research and Innovation Agency (Badan Riset dan Inovasi Nasional/BRIN) of the Republic of Indonesia: Genome Betta spp. (
                <ext-link ext-link-type="uri" xlink:href="https://hdl.handle.net/20.500.12690/RIN/LEOQPP">https://hdl.handle.net/20.500.12690/RIN/LEOQPP</ext-link>).
                <sup>
                    <xref ref-type="bibr" rid="ref64">64</xref>
                </sup>
            </p>
            <sec id="sec25">
                <title>Extended data</title>
                <p>All extended data have been deposited in figshare (DOI: 
                    <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.6084/m9.figshare.31189546">https://doi.org/10.6084/m9.figshare.31189546</ext-link>).
                    <sup>
                        <xref ref-type="bibr" rid="ref65">65</xref>
                    </sup> The extended data include the following:</p>
                <p>Suppl Fig 1. The meristic (A) and morphometric (B) characters of 
                    <italic toggle="yes">Betta spp.</italic>
                </p>
                <p>Suppl Fig 2. A comparative analysis of the Melanocortin 1 Receptor (MC1R) and Paired box 7 (PAX7) protein sequences among 
                    <italic toggle="yes">B. burdigala</italic>, 
                    <italic toggle="yes">B. chloropharynx</italic>, and 
                    <italic toggle="yes">B. schalleri</italic>, alongside 
                    <italic toggle="yes">B. splendens, Anabas testudineus, Channa argus, Oreochromis niloticus, Danio rerio, and Carassius auratus.</italic> (A) A phylogenetic tree derived from MC1R protein alignments across nine fish species. (B) Multiple Sequence Alignment of the PAX7 MC1R protein in these nine fish species. (C) A phylogenetic tree derived from PAX7 protein alignments across nine fish species. (D) Multiple Sequence Alignment of the PAX7 protein in these nine fish species. The complete protein sequence alignment of MC1R and PAX7 are available in Supplementary file 2 and Supplementary file 3 respectively.</p>
                <p>Supplementary file 1. Protein alignment of CSF1R1 in 9 fishes.clustal_num</p>
                <p>Supplementary file 2. Protein alignment of MC1R in 9 fishes.clustal_num</p>
                <p>Supplementary file 3. Protein alignment of PAX7 in 9 fishes.clustal_num</p>
            </sec>
            <sec id="sec26">
                <title>Reporting guidelines</title>
                <p>The complete checklists of ARRIVE 2.0 reporting guidelines is available at 
                    <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.6084/m9.figshare.31136455">https://doi.org/10.6084/m9.figshare.31136455</ext-link>.
                    <sup>
                        <xref ref-type="bibr" rid="ref11">11</xref>
                    </sup>
                </p>
                <p>All the underlying and extended data of this study are openly available under the terms of The 
                    <ext-link ext-link-type="uri" xlink:href="https://creativecommons.org/licenses/by/4.0/">CC BY 4.0 license (Creative Commons Attribution 4.0 International)</ext-link>.</p>
            </sec>
        </sec>
        <ack>
            <title>Acknowledgements</title>
            <p>We extend our sincere appreciation to the Directorate of Research and Community Service (DPPM) of Ministry of Higher Education, Science and Technology, and the Chairman of LLDIKTI II for their financial support of this research. We also express our gratitude to the Rector of Universitas Muhammadiyah Palembang, the Chairman of LPPM Universitas Muhammadiyah Palembang, and the Dean of the Faculty of Agriculture at Universitas Muhammadiyah Palembang for their support in the execution of this research. Additionally, we acknowledge PT. Timah Tbk. and Yayasan Ikan Endemik Bangka Belitung for facilitating this research. The authors are grateful for the facilities and scientific and technical support provided by the Whole Genome Sequencing Laboratory, National Research and Innovation Agency through E-Layanan Sains, Badan Riset dan Inovasi Nasional. We also wish to thank Integrated Genome Factory (IGF) Faculty of Biology UGM for granting access to computing facilities. During the preparation of this work, we used Paperpal to improve grammar and sentence structure in the manuscript. After using this tool, we reviewed and edited the content as needed and take full responsibility for the content of the publication.</p>
        </ack>
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    <sub-article article-type="reviewer-report" id="report457789">
        <front-stub>
            <article-id pub-id-type="doi">10.5256/f1000research.192703.r457789</article-id>
            <title-group>
                <article-title>Reviewer response for version 1</article-title>
            </title-group>
            <contrib-group>
                <contrib contrib-type="author">
                    <name>
                        <surname>Kron</surname>
                        <given-names>Nicholas S</given-names>
                    </name>
                    <xref ref-type="aff" rid="r457789a1">1</xref>
                    <xref ref-type="aff" rid="r457789a2">2</xref>
                    <role>Referee</role>
                    <uri content-type="orcid">https://orcid.org/0000-0002-2274-003X</uri>
                </contrib>
                <aff id="r457789a1">
                    <label>1</label>University of Miami, Rickenbacker Cswy, Miami, USA</aff>
                <aff id="r457789a2">
                    <label>2</label>Genevia Technologies, Finland, Finland</aff>
            </contrib-group>
            <author-notes>
                <fn fn-type="conflict">
                    <p>
                        <bold>Competing interests: </bold>No competing interests were disclosed.</p>
                </fn>
            </author-notes>
            <pub-date pub-type="epub">
                <day>5</day>
                <month>3</month>
                <year>2026</year>
            </pub-date>
            <permissions>
                <copyright-statement>Copyright: &#x00a9; 2026 Kron NS</copyright-statement>
                <copyright-year>2026</copyright-year>
                <license xlink:href="https://creativecommons.org/licenses/by/4.0/">
                    <license-p>This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</license-p>
                </license>
            </permissions>
            <related-article ext-link-type="doi" id="relatedArticleReport457789" related-article-type="peer-reviewed-article" xlink:href="10.12688/f1000research.174779.1"/>
            <custom-meta-group>
                <custom-meta>
                    <meta-name>recommendation</meta-name>
                    <meta-value>approve-with-reservations</meta-value>
                </custom-meta>
            </custom-meta-group>
        </front-stub>
        <body>
            <p>
                <bold>Summary</bold>
            </p>
            <p> In &#x201c;Beyond the Beauty: Meristic and Genomic Signatures of Bangka&#x2019;s Endemic Betta Fishes&#x201d;, Helmizuryani et al. describe the collection, sampling, genome assembly and annotation, and comparative genomic analysis of three species of the genus 
                <italic>Betta</italic> from the Bangka islands of Indonesia. The authors demonstrate high quality, sub-chromosome level genome assemblies using Oxford Nanopore sequencing and established long read assembly and annotation workflows. Based on genome annotation results, the authors describe the genomes of the three species as highly colinear and consistent, with minor variation among them possibly relating to evolutionary divergence among the three, with special attention paid to pigmentation associated genes. &#x00a0;&#x00a0;</p>
            <p> </p>
            <p> 
                <bold>Comments</bold>
            </p>
            <p> The study employs commonly used open-source tools and standard methodologies for assembly and annotation. The genomic resources generated by this study are novel and valuable contributions and will surely be useful for future studies in these species and for teleost and vertebrate genomics more broadly. &#x00a0;</p>
            <p> The manuscript would benefit from proof reading for spelling, grammar, consistency, etc.: 
                <list list-type="bullet">
                    <list-item>
                        <p>Consistency of italicization for species names throughout.</p>
                    </list-item>
                    <list-item>
                        <p>Introduction: &#x201c;The number of endemic wild Betta distribution and diversity of Southeast Asia has been identified for 16 years in Thailand (2 species) and Indonesia (9 species)&#x201d;</p>
                    </list-item>
                    <list-item>
                        <p>Introduction: &#x201c;Three species of Betta spp. were endemic, i.e., 
                            <italic>Betta burdigala</italic>, 
                            <italic>Betta chloropharynx</italic>, and 
                            <italic>Betta schalleri.&#x201d;</italic>
                        </p>
                    </list-item>
                    <list-item>
                        <p>Introduction: &#x201c;The genetic studies of the endemic fish Betta spp. on Bangka Island have&#x2026;&#x201d;</p>
                    </list-item>
                    <list-item>
                        <p>Introduction: &#x201c;However, the whole genome for the evolution of the endemic fish Betta spp. on Bangka Island hasn&#x2019;t been revealed.&#x201d;</p>
                    </list-item>
                    <list-item>
                        <p>Introduction: &#x201c;High-quality genomic data could be used for Long-read sequencing and high-throughput chromosome (Hi-C) technology.&#x201d;</p>
                    </list-item>
                    <list-item>
                        <p>The authors reference the benefits of Hi-C in their introduction but do not use Hi-C in their analysis.</p>
                    </list-item>
                </list> </p>
            <p> 
                <bold>Are sufficient details of methods and analysis provided to allow replication by others? (partly)</bold>
            </p>
            <p> The authors provide the software and version numbers to software used which is appreciated and facilitates reproducibility. However, the authors do not specify if software was used with default parameters or parameters deviating from default. These can be critical for reproducing or evaluating the analyses done, especially for tools like BLAST. Nor do the authors provide links to repositories (e.g. github, zenodo) of scripts used for verification and/or reproduction of methods. I would strongly recommend a remark in the methods stating that unless otherwise specified, default parameters are used, and explicit description when non-standard parameters are used in text or a supplement. If possible, provide access to analysis scripts in their entirety.</p>
            <p> 
                <bold>Are the conclusions drawn adequately supported by the results? (Partly)</bold> 
                <list list-type="order">
                    <list-item>
                        <p>The assembly BUSCO assessments have a very low duplicate BUSCO count but the gene model level BUSCO assessments are much higher (~20%). This is not unexpected as isoform redundancy, pseudo-genes, etc do crop up and can impact BUSCO analysis. Have the authors run the annotation level BUSCO analysis using only longest isoforms to verify? It is not clear from the methods how exactly BUSCO was run on the annotation results.</p>
                    </list-item>
                    <list-item>
                        <p>The authors do not mention any secondary verification on the gene models / predicted duplicates to verify they are not artifacts/pseudogenes/etc. While automated pipelines like funannotate are powerful and convenient, secondary validation of gene models is often needed especially if proceeding to duplication analysis with tools like MCScanX/OrthoFinder/Caf&#x00e9;.</p>
                    </list-item>
                    <list-item>
                        <p>The authors do not describe the assembly or annotation of the mitochondrial genome of each species. While not strictly necessary per se, these data are readily isolated from the long reads and would provide a more complete picture of the genomes and further context to the syntenty-based phylogenetic analysis.</p>
                    </list-item>
                    <list-item>
                        <p>The authors use RagTag for reference-based scaffolding of assembled contigs. In the absence of Hi-C/OmniC data, this is a suitable alternative, especially given the authors have access to a closely related congener 
                            <italic>Betta splendens</italic>. This success of this approach is determined by the completeness/continuity/scaffold size of the input assemblies and the reference. Given this, comparisons of the assembly and annotation statistics of the new assemblies to the reference would provide important context for these assemblies. This would improve the ability of readers to gauge the quality of the assemblies and the success of the method. For example, a table produced by a tool like QUAST that compares the major assembly statistics would be suitable.</p>
                    </list-item>
                    <list-item>
                        <p>The RagTag method used can cause scaffolded assemblies to resemble the reference genome in terms of structure, especially for more fragmented/low coverage assemblies. The authors need to clearly discuss the potential impact of these potential artefacts on their collinearity results and conclusions.</p>
                    </list-item>
                    <list-item>
                        <p>Given the authors are using gene models for their comparative analysis (not sequences directly verified with molecular methods), the authors should report support for identified protein insertions with primary data (e.g. insertion spanning long reads, depth of coverage at the insertion site, etc.). &#x00a0;&#x00a0;</p>
                    </list-item>
                    <list-item>
                        <p>In the discussion, the authors make claims about purifying selection, rate of gene evolution, lineage specific selection, etc.. These are inferences that can only be drawn with population genetic data. These claims are improper for the data presented (e.g. assemblies of single individuals) and should be removed or qualified as such.</p>
                    </list-item>
                </list> 
                <bold>Additional comments</bold> 
                <list list-type="order">
                    <list-item>
                        <p>The manuscript would be strengthened by reporting metrics from initial k-mer profiling with GenomeScope2. These could be reported in the form of the annotated k-mer distribution plot generated by GenomeScope2.</p>
                    </list-item>
                    <list-item>
                        <p>The authors do not describe any methods for decontamination (either technical or biological). If these were not performed, this should be explicitly noted. If they were, what methods were employed and if they were pre-assembly or post assembly should be specified.</p>
                    </list-item>
                    <list-item>
                        <p>The authors do make publicly available the raw data, genome assemblies, and annotations. I would also recommend additionally submitting the repeats to public databases such as Dfam or FishTEDB.</p>
                    </list-item>
                </list>
            </p>
            <p>Is the work clearly and accurately presented and does it cite the current literature?</p>
            <p>Yes</p>
            <p>If applicable, is the statistical analysis and its interpretation appropriate?</p>
            <p>I cannot comment. A qualified statistician is required.</p>
            <p>Are all the source data underlying the results available to ensure full reproducibility?</p>
            <p>Yes</p>
            <p>Is the study design appropriate and is the work technically sound?</p>
            <p>Yes</p>
            <p>Are the conclusions drawn adequately supported by the results?</p>
            <p>Partly</p>
            <p>Are sufficient details of methods and analysis provided to allow replication by others?</p>
            <p>Partly</p>
            <p>Reviewer Expertise:</p>
            <p>bioinformatics, marine biology</p>
            <p>I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.</p>
        </body>
        <sub-article article-type="response" id="comment16220-457789">
            <front-stub>
                <contrib-group>
                    <contrib contrib-type="author">
                        <name>
                            <surname>Nurhidayat</surname>
                            <given-names>Luthfi</given-names>
                        </name>
                        <aff>Faculty of Biology Universitas Gadjah Mada, Indonesia</aff>
                    </contrib>
                </contrib-group>
                <author-notes>
                    <fn fn-type="conflict">
                        <p>
                            <bold>Competing interests: </bold>We declare that we do not have any competing interest.</p>
                    </fn>
                </author-notes>
                <pub-date pub-type="epub">
                    <day>18</day>
                    <month>5</month>
                    <year>2026</year>
                </pub-date>
            </front-stub>
            <body>
                <p>
                    <bold>Comments</bold>
                </p>
                <p> The study employs commonly used open-source tools and standard methodologies for assembly and annotation. The genomic resources generated by this study are novel and valuable contributions and will surely be useful for future studies in these species and for teleost and vertebrate genomics more broadly. &#x00a0;</p>
                <p> The manuscript would benefit from proof reading for spelling, grammar, consistency, etc.: 
                    <list list-type="bullet">
                        <list-item>
                            <p>Consistency of italicization for species names throughout.</p>
                        </list-item>
                    </list> 
                    <bold>Response: </bold>
                </p>
                <p> We have checked and fixed the consistency of italicization for species names within the revised manuscript.</p>
                <p> &#x00a0; 
                    <list list-type="bullet">
                        <list-item>
                            <p>Introduction: &#x201c;The number of endemic wild Betta distribution and diversity of Southeast Asia has been identified for 16 years in Thailand (2 species) and Indonesia (9 species)&#x201d;</p>
                        </list-item>
                    </list> 
                    <bold>Response:</bold>
                </p>
                <p> We have revised it to &#x201c;Indonesia harbors nine wild Betta species classified as Critically Endangered (CN) and seven species categorized as Endangered (EN). In comparison, Thailand contains two Critically Endangered (CE) wild Betta species and one Endangered (EN) species&#x201d;</p>
                <p> &#x00a0; 
                    <list list-type="bullet">
                        <list-item>
                            <p>Introduction: &#x201c;Three species of Betta spp. were endemic, i.e.,&#x00a0;
                                <italic>Betta burdigala</italic>,&#x00a0;
                                <italic>Betta chloropharynx</italic>, and&#x00a0;
                                <italic>Betta schalleri.&#x201d;</italic>
                            </p>
                        </list-item>
                    </list> 
                    <bold>Response:</bold>
                </p>
                <p> We have revised it to &#x201c;Three 
                    <italic>Betta</italic> species&#x2014;
                    <italic>B. burdigala</italic>, 
                    <italic>B. chloropharynx</italic>, and 
                    <italic>B. schalleri</italic>&#x2014;are endemic to the Bangka Islands&#x201d; 
                    <list list-type="bullet">
                        <list-item>
                            <p>Introduction: &#x201c;The genetic studies of the endemic fish Betta spp. on Bangka Island have&#x2026;&#x201d;</p>
                        </list-item>
                    </list> 
                    <bold>Response: </bold>
                </p>
                <p> We have change it to &#x201c;Previous studies on the endemic 
                    <italic>Betta</italic> species from Bangka Island have included genetic analyses based on mitochondrial DNA and eDNA metabarcoding, as well as comprehensive morphological examinations, all of which have contributed to clarifying the genetic relationships and taxonomic status of these species.&#x201d; 
                    <list list-type="bullet">
                        <list-item>
                            <p>Introduction: &#x201c;However, the whole genome for the evolution of the endemic fish Betta spp. on Bangka Island hasn&#x2019;t been revealed.&#x201d;</p>
                        </list-item>
                    </list> 
                    <bold>Response: </bold>
                </p>
                <p> We have revised it to &#x201c;However, the whole-genome evolutionary landscape of the endemic 
                    <italic>Betta</italic> species from Bangka Island has not yet been explored.&#x201d; 
                    <list list-type="bullet">
                        <list-item>
                            <p>Introduction: &#x201c;High-quality genomic data could be used for Long-read sequencing and high-throughput chromosome (Hi-C) technology.&#x201d;</p>
                        </list-item>
                    </list> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for noticing the mistakes.&#x00a0; We have revised it to &#x201c;High-quality genomic data can be generated using long-read sequencing technologies such as Oxford Nanopore sequencing, which enables the production of highly contiguous genome assemblies.....&#x201d; 
                    <list list-type="bullet">
                        <list-item>
                            <p>The authors reference the benefits of Hi-C in their introduction but do not use Hi-C in their analysis.</p>
                        </list-item>
                    </list> 
                    <bold>Response: </bold>
                </p>
                <p> We have revised the Introduction section by removing the Hi-C-related description to better align the manuscript with the actual sequencing and assembly strategy used in this study, which was based on Oxford Nanopore long-read sequencing without Hi-C data. The revised text now reads:</p>
                <p> &#x201c;High-quality genomic data can be generated using long-read sequencing technologies such as Oxford Nanopore sequencing, which enables the production of highly contiguous genome assemblies. These technologies help resolve complex repetitive regions and haplotype heterozygosity, both of which are major sources of genome assembly errors
                    <sup>7</sup>.&#x201d;</p>
                <p> This revision ensures that the Introduction more accurately reflects the methodologies and analyses performed in the present study.</p>
                <p> </p>
                <p> </p>
                <p> 
                    <bold>Are sufficient details of methods and analysis provided to allow replication by others? (partly)</bold>
                </p>
                <p> The authors provide the software and version numbers to software used which is appreciated and facilitates reproducibility. However, the authors do not specify if software was used with default parameters or parameters deviating from default. These can be critical for reproducing or evaluating the analyses done, especially for tools like BLAST. Nor do the authors provide links to repositories (e.g. github, zenodo) of scripts used for verification and/or reproduction of methods. I would strongly recommend a remark in the methods stating that unless otherwise specified, default parameters are used, and explicit description when non-standard parameters are used in text or a supplement. If possible, provide access to analysis scripts in their entirety.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this valuable suggestion. We agree that explicit reporting of software parameters and analytical workflows is essential for ensuring reproducibility and transparency. In response, we have revised the Methods section to clarify that, unless otherwise specified, all software tools were executed using their default parameters. We also added explicit descriptions for analyses in which non-default settings or filtering criteria were applied.</p>
                <p> Specifically, we added the following sentence to clarify the BLAST settings used in the duplication analysis:</p>
                <p> &#x201c;The analyses were performed using an E-value threshold of 1e&#x2212;3, with results limited to a maximum of five target hits per query sequence and output generated in tabular format (outfmt 6). Computations were executed using 12 parallel threads, while all other parameters were retained at their default settings.&#x201d;</p>
                <p> Regarding the analysis scripts, most workflows in this study were conducted using established bioinformatics software through standard command-line execution rather than extensive custom scripting. Therefore, we focused on providing detailed descriptions of the analytical workflows, software versions, and key command parameters directly within the manuscript and supplementary materials to facilitate reproducibility. We also ensured that all non-default settings and critical filtering parameters are now explicitly documented in the revised manuscript.</p>
                <p> We appreciate the reviewer&#x2019;s recommendation, which helped improve the methodological clarity, transparency, and reproducibility of the study.</p>
                <p> </p>
                <p> 
                    <bold>Are the conclusions drawn adequately supported by the results? (Partly)</bold>
                </p>
                <p> 1. The assembly BUSCO assessments have a very low duplicate BUSCO count but the gene model level BUSCO assessments are much higher (~20%). This is not unexpected as isoform redundancy, pseudo-genes, etc do crop up and can impact BUSCO analysis. Have the authors run the annotation level BUSCO analysis using only longest isoforms to verify? It is not clear from the methods how exactly BUSCO was run on the annotation results.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this important observation. We agree that annotation-level BUSCO assessments can show elevated duplicated BUSCO proportions due to the inclusion of multiple transcript isoforms, fragmented predictions, or potential pseudogene annotations.</p>
                <p> In our study, the BUSCO assessment of the predicted gene models was performed using the complete predicted protein set generated from the annotation pipeline, including all annotated isoforms, rather than restricting the analysis to only the longest isoform per gene. We acknowledge that this approach may contribute to the higher duplicated BUSCO proportion observed at the annotation level compared with the genome assembly-level BUSCO assessment.</p>
                <p> To clarify this point, we have revised the Methods section to explicitly describe how BUSCO was conducted on the annotation results, including the use of the full predicted protein dataset. We also added clarification in the Results that the elevated duplicated BUSCO values at the annotation level likely reflect transcript isoform redundancy and annotation complexity rather than extensive true biological duplication.</p>
                <p> Nevertheless, the overall high completeness of the predicted protein sets still supports the quality and comprehensiveness of the genome annotations generated in this study.</p>
                <p> </p>
                <p> 2. The authors do not mention any secondary verification on the gene models / predicted duplicates to verify they are not artifacts/pseudogenes/etc. While automated pipelines like funannotate are powerful and convenient, secondary validation of gene models is often needed especially if proceeding to duplication analysis with tools like MCScanX/OrthoFinder/Caf&#x00e9;.</p>
                <p> 
                    <bold>Response: </bold>
                </p>
                <p> Thank you for this important comment. We agree that automated genome annotation pipelines may occasionally retain fragmented gene models, pseudogenes, or assembly-related artifacts, and that additional validation can further improve confidence in downstream duplication analyses.</p>
                <p> In our study, structural gene prediction was performed using GALBA within the BRAKER framework. The GALBA pipeline incorporates protein evidence from closely related species to improve gene prediction accuracy and reduce false-positive annotations compared with purely ab initio approaches. Subsequently, Funannotate was used for functional annotation processing, including integration of functional annotation results into the GFF3 files and generation of submission-ready annotation files.</p>
                <p> The resulting annotations showed high completeness based on BUSCO assessment of the predicted protein sets, supporting the overall quality of the gene models used in downstream analyses. Consequently, the duplication analyses performed using MCScanX were based on curated predicted protein-coding genes generated from this evidence-supported annotation workflow.</p>
                <p> Nevertheless, we acknowledge that some predicted duplicates may still include fragmented annotations or non-functional copies that cannot be conclusively distinguished without additional transcriptomic, population-level, or experimental validation. To address this concern, we revised the manuscript in the &#x201c;Structural and Functional Annotation and Gene Duplication Analysis&#x201d; subsection of the Results section by adding the following statement:</p>
                <p> &#x201c;The identified duplication patterns should therefore be interpreted as comparative genomic patterns inferred from predicted gene models and homologous gene relationships, rather than as definitive evidence of fully functional duplicated genes.&#x201d;</p>
                <p> </p>
                <p> 3. The authors do not describe the assembly or annotation of the mitochondrial genome of each species. While not strictly necessary per se, these data are readily isolated from the long reads and would provide a more complete picture of the genomes and further context to the syntenty-based phylogenetic analysis.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this insightful suggestion. We agree that mitochondrial genome assemblies can provide valuable complementary information for comparative and phylogenetic analyses. In the present study, however, our primary focus was on the nuclear genome assemblies and comparative analyses related to genome structure, synteny, and pigmentation-associated genes.</p>
                <p> We have in fact successfully assembled the mitochondrial genomes of the studied 
                    <italic>Betta</italic> species from the long-read sequencing data. However, these mitochondrial genome datasets are currently being analyzed in a separate study addressing distinct biological questions related to mitochondrial evolution and phylogeography. To avoid overlap between manuscripts and maintain a clear scope for the present study, we therefore chose not to include the mitochondrial genome analyses here.</p>
                <p> Nevertheless, we acknowledge the value of mitochondrial genomic information and have added a statement in the manuscript clarifying that mitochondrial genome assemblies were recovered from the sequencing data and will be reported separately in a dedicated study.</p>
                <p> </p>
                <p> 4.&#x00a0;The authors use RagTag for reference-based scaffolding of assembled contigs. In the absence of Hi-C/OmniC data, this is a suitable alternative, especially given the authors have access to a closely related congener&#x00a0;
                    <italic>Betta splendens</italic>. This success of this approach is determined by the completeness/continuity/scaffold size of the input assemblies and the reference. Given this, comparisons of the assembly and annotation statistics of the new assemblies to the reference would provide important context for these assemblies. This would improve the ability of readers to gauge the quality of the assemblies and the success of the method. For example, a table produced by a tool like QUAST that compares the major assembly statistics would be suitable.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this constructive suggestion. We agree that comparison of the newly generated assemblies against the reference genome provides important context for evaluating assembly quality and the effectiveness of the reference-guided scaffolding strategy.</p>
                <p> we performed additional assembly quality assessment using QUAST and have added the results as 
                    <bold>Supplementary file 5. QUAST assembly quality assessment statistics for the three 
                        <italic>Betta</italic> genome assemblies </bold>in figshare (DOI: 
                    <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.6084/m9.figshare.31189546.v3">https://doi.org/10.6084/m9.figshare.31189546.v3</ext-link> ). The QUAST report includes major assembly statistics such as contig number, total assembly size, N50/NG50, largest contig size, GC content, duplication ratio, gap content, and misassembly statistics, together with alignment-based comparisons against the reference genome.</p>
                <p> The QUAST assessment showed that all three assemblies possess high contiguity, with contig N50 values ranging from ~19.3&#x2013;20.1 Mb and largest contigs exceeding 33 Mb. In addition, the assemblies exhibited very low numbers of detected misassemblies and low gap content, supporting the overall structural quality of the assemblies.</p>
                <p> We believe the inclusion of the QUAST assessment substantially improves the contextual evaluation and transparency of the genome assemblies presented in this study.</p>
                <p> </p>
                <p> 5. The RagTag method used can cause scaffolded assemblies to resemble the reference genome in terms of structure, especially for more fragmented/low coverage assemblies. The authors need to clearly discuss the potential impact of these potential artefacts on their collinearity results and conclusions.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this important comment. We acknowledge that the use of reference-guided scaffolding may influence large-scale structural organization and potentially increase apparent similarity to the reference genome. In our study, however, the genome assemblies were initially generated 
                    <italic>de novo</italic> from Oxford Nanopore long reads, while RagTag was used only during the scaffolding stage to improve chromosome-scale continuity.</p>
                <p> To address this concern, we have revised the Results and Discussion sections to more explicitly acknowledge the potential limitations associated with reference-guided scaffolding. We also clarified that the collinearity analyses were performed using annotated protein-coding genes and orthologous gene order on the scaffolded assemblies, rather than direct whole-genome nucleotide alignments. Therefore, the syntenic patterns presented in this study primarily reflect conservation of gene content and relative gene order, rather than exact chromosome-scale structural identity.</p>
                <p> In addition, we have moderated the wording throughout the manuscript to avoid overinterpretation. Statements implying definitive structural conservation or phylogenetic inference have been revised to more cautious descriptions such as &#x201c;broadly conserved syntenic patterns&#x201d; and &#x201c;patterns generally consistent with established taxonomic relationships.&#x201d; We now also explicitly note that these observations should be interpreted within the context of reference-guided scaffolding.</p>
                <p> Nevertheless, because the assemblies themselves were generated 
                    <italic>de novo</italic> and the comparative analyses were based on orthologous gene annotations rather than direct reference-guided genome alignment, we believe the analyses still provide informative comparative insights into genome organization among the examined 
                    <italic>Betta</italic> species.</p>
                <p> </p>
                <p> 6. Given the authors are using gene models for their comparative analysis (not sequences directly verified with molecular methods), the authors should report support for identified protein insertions with primary data (e.g. insertion spanning long reads, depth of coverage at the insertion site, etc.). &#x00a0;
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this important suggestion. To validate the inferred insertion identified from the gene model, we mapped Oxford Nanopore long reads back to the assembled genome. Coverage analysis revealed consistent read depth across the insertion locus (~70&#x2013;88&#x00d7;), with no evidence of local coverage collapse or assembly breakpoints, thereby supporting the authenticity of the insertion. In addition, long-read alignments spanning the insertion region were visually inspected using Integrative Genomics Viewer and have been included in the Supplementary Materials deposited in figshare (DOI: https://doi.org/10.6084/m9.figshare.31189546.v2 ). The following supplementary materials have been added:</p>
                <p> Supplementary Figure S3. Validation of the CSF1R1 insertion using Oxford Nanopore long-read alignments. Coverage depth across the insertion locus remained consistent (~70&#x2013;88&#x00d7;), and multiple long reads continuously spanned the insertion region, supporting the authenticity of the predicted insertion and excluding local assembly artifacts.</p>
                <p> Supplementary File S4. Coverage depth of the CSF1R1_1 region based on Oxford Nanopore long-read alignments.</p>
                <p> </p>
                <p> 7. In the discussion, the authors make claims about purifying selection, rate of gene evolution, lineage specific selection, etc.. These are inferences that can only be drawn with population genetic data. These claims are improper for the data presented (e.g. assemblies of single individuals) and should be removed or qualified as such.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this valuable comment. We agree that strong evolutionary inferences such as purifying selection, lineage-specific selection, or adaptive evolution cannot be conclusively established from genome assemblies derived from single individuals without population-level genomic data. To avoid overinterpretation, we have revised the Discussion section to use more cautious and descriptive language that better reflects the scope of the current dataset.</p>
                <p> The following changes were made in the revised manuscript: 
                    <list list-type="bullet">
                        <list-item>
                            <p>&#x201c;...reflecting strong purifying selection on this essential signaling pathway&#x201d;</p>
                            <p> was revised to</p>
                            <p> &#x201c;...reflecting high sequence conservation and potential evolutionary constraints on this essential signaling pathway.&#x201d;</p>
                        </list-item>
                        <list-item>
                            <p>&#x201c;Similarly, the non-concordant evolution of MC1R, despite its variable role in teleost pigmentation, suggests relaxed constraint or functional innovation within the 
                                <italic>Betta</italic> lineage.&#x201d;</p>
                            <p> was revised to</p>
                            <p> &#x201c;Similarly, the non-concordant evolution of MC1R, despite its variable role in teleost pigmentation, is consistent with high sequence divergence that may warrant future investigation into potential regulatory or functional divergence within the 
                                <italic>Betta</italic> lineage.&#x201d;</p>
                        </list-item>
                        <list-item>
                            <p>&#x201c;...may hint at ongoing lineage-specific regulatory or structural adaptations...&#x201d;</p>
                            <p> was revised to</p>
                            <p> &#x201c;...may hint at lineage-specific regulatory or structural variations.&#x201d;</p>
                        </list-item>
                        <list-item>
                            <p>&#x201c;...potentially linked to ecological adaptations or evolutionary divergence...&#x201d;</p>
                            <p> was revised to</p>
                            <p> &#x201c;...potentially linked to evolutionary divergence among these lineages. However, population-level genomic data will be required to definitively connect these structural variations to specific ecological adaptations.&#x201d;</p>
                        </list-item>
                    </list> These revisions were made throughout the Discussion section to ensure that the interpretations remain appropriately conservative and fully supported by the available data.</p>
                <p> </p>
                <p> 
                    <bold>Additional comments</bold>
                </p>
                <p> 1. The manuscript would be strengthened by reporting metrics from initial k-mer profiling with GenomeScope2. These could be reported in the form of the annotated k-mer distribution plot generated by GenomeScope2.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for the suggestion. We have added the 21-mer profiling analysis to Figure 3. Accordingly, we have revised the figure caption as follows:</p>
                <p> &#x201c;Figure 3. 21-mer&#x2013;based genome size estimation (upper panels) and summary of genome assembly characteristics (lower panels) for 
                    <italic>Betta burdigala</italic>, 
                    <italic>Betta chloropharynx</italic>, and 
                    <italic>Betta schalleri</italic>.&#x201d;</p>
                <p> </p>
                <p> 2. The authors do not describe any methods for decontamination (either technical or biological). If these were not performed, this should be explicitly noted. If they were, what methods were employed and if they were pre-assembly or post assembly should be specified.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for noticing. We apologize for not mentioning the contamination screening method used for our assembly. Prior to assembly, we conducted adapter contamination screening using Porechop_ABI, and post-assembly, we screened for foreign contamination using FCS-GX. We have now included the contamination screening details in the methods section under the &#x201c;Genome Assembly and Annotation&#x201d; subsection.</p>
                <p> 
                    <italic>&#x201c;</italic>
                    <italic>Adapter contamination screening was performed using Porechop_ABI prior to assembly&#x201d;</italic>
                </p>
                <p> And 
                    <italic>&#x201c;</italic>
                    <italic>Foreign contamination was screened and removed using NCBI FCS-GX prior to scaffolding&#x201d;</italic>
                </p>
                <p> </p>
                <p> 3. The authors do make publicly available the raw data, genome assemblies, and annotations. I would also recommend additionally submitting the repeats to public databases such as Dfam or FishTEDB.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Many thanks for the suggestion. We plan to submit it to the DFAM database for the near future.</p>
            </body>
        </sub-article>
    </sub-article>
    <sub-article article-type="reviewer-report" id="report461103">
        <front-stub>
            <article-id pub-id-type="doi">10.5256/f1000research.192703.r461103</article-id>
            <title-group>
                <article-title>Reviewer response for version 1</article-title>
            </title-group>
            <contrib-group>
                <contrib contrib-type="author">
                    <name>
                        <surname>Xing</surname>
                        <given-names>Bingpeng</given-names>
                    </name>
                    <xref ref-type="aff" rid="r461103a1">1</xref>
                    <role>Referee</role>
                </contrib>
                <aff id="r461103a1">
                    <label>1</label>Third Institute of Oceanography Ministry of Natural Resources, Xiamen, China</aff>
            </contrib-group>
            <author-notes>
                <fn fn-type="conflict">
                    <p>
                        <bold>Competing interests: </bold>No competing interests were disclosed.</p>
                </fn>
            </author-notes>
            <pub-date pub-type="epub">
                <day>26</day>
                <month>2</month>
                <year>2026</year>
            </pub-date>
            <permissions>
                <copyright-statement>Copyright: &#x00a9; 2026 Xing B</copyright-statement>
                <copyright-year>2026</copyright-year>
                <license xlink:href="https://creativecommons.org/licenses/by/4.0/">
                    <license-p>This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</license-p>
                </license>
            </permissions>
            <related-article ext-link-type="doi" id="relatedArticleReport461103" related-article-type="peer-reviewed-article" xlink:href="10.12688/f1000research.174779.1"/>
            <custom-meta-group>
                <custom-meta>
                    <meta-name>recommendation</meta-name>
                    <meta-value>approve-with-reservations</meta-value>
                </custom-meta>
            </custom-meta-group>
        </front-stub>
        <body>
            <p>This manuscript focuses on three endemic Betta fishes from Bangka Island&#x2014;
                <italic>Betta burdigala, B. chloropharynx, and B. schalleri&#x2014;</italic>conducting an integrated study of meristic analysis and whole-genome assembly, and it makes the related sequencing data and assembly results publicly available. For endemic fishes of Bangka Island peatland wetlands, this study provides the first genomic resources and has potential value for conservation genomics and species evolution research.</p>
            <p> Overall, the data release is relatively complete, and the assembly contiguity and BUSCO completeness are high, meeting the basic requirements of a resource-type genome paper. However, the manuscript still needs strengthening in the following aspects:</p>
            <p> 1.&#x00a0;&#x00a0; &#x00a0;Reference genome&#x2013;guided scaffolding may affect structural and collinearity conclusions. The authors used RagTag together with the Betta splendens reference genome for scaffold construction. This approach is feasible for generating chromosome-scale assemblies, but it may also introduce structural bias to some extent, making the assembly closer to the reference genome structure. The conclusions in the current manuscript such as &#x201c;high collinearity,&#x201d; &#x201c;closer phylogenetic relationships,&#x201d; and &#x201c;highly conserved structure&#x201d; are all based on this scaffolding result; therefore: it is recommended to clearly state the potential limitations of reference-guided scaffolding in the Methods and Discussion; and clarify whether the collinearity analysis was based on the original contigs or the reference-guided scaffolds.</p>
            <p> 2.&#x00a0;&#x00a0; &#x00a0;The sample size is limited, and over-inference at the species level should be avoided. The morphological analysis includes only three individuals per species, and genome sequencing includes only one individual per species. This is acceptable for a resource-type paper, but inferences in the following aspects should be more cautious: patterns of interspecific differences; gene duplication dynamics; specific gene insertion events; and inference of evolutionary divergence time.</p>
            <p> 3.&#x00a0;&#x00a0; &#x00a0;The two &#x201c;large insertions&#x201d; in CSF1RA require stronger supporting evidence. The manuscript reports that CSF1RA in B. burdigala contains two large amino-acid insertions and speculates that they may affect pigment regulation. This result has potential novelty but currently lacks the following validation: long-read coverage; read-level support at the insertion boundaries; whether there are low-complexity or repetitive-sequence artifacts; and whether assembly or annotation errors have been excluded.</p>
            <p> 4.&#x00a0;&#x00a0; &#x00a0;Evidence from a single-gene phylogenetic analysis is limited. The authors constructed a phylogenetic tree using the single gene CSF1RA and compared it with the NCBI taxonomy tree. A single-gene tree can only serve as a consistency check and cannot provide strong support for phylogenetic relationships.</p>
            <p> 5.&#x00a0;&#x00a0; &#x00a0;Genome quality assessment metrics can still be strengthened. The manuscript reports N50, scaffold number, BUSCO, GC content, and gap percentage; these metrics are relatively basic. It is recommended to add sequencing depth (estimated coverage); read length N50 or mean read length; k-mer completeness analysis; assembly quality value (QV); and contamination detection methods (if any). Adding 2&#x2013;3 of the above metrics can significantly improve confidence in the assembly.</p>
            <p> 6.&#x00a0;&#x00a0; &#x00a0;The background statements in the Introduction needs revision. There are unclear and illogical sentences in the Introduction, such as the description of &#x201c;16 years&#x201d; and &#x201c;2 species in Thailand and 9 species in Indonesia,&#x201d; which is confusing. Rewrite the relevant paragraphs to make the logic clearer; describe more accurately recent progress in taxonomy and diversity research of the genus Betta; and standardize IUCN status as &#x201c;Critically Endangered (CR)&#x201d; or &#x201c;Endangered (EN)&#x201d; with clear citations.</p>
            <p> 7.&#x00a0;&#x00a0; &#x00a0;The Latin name format is not standardized. The manuscript should be unified: genus and species names in italics, such as Betta burdigala; abbreviated form B. burdigala; in &#x201c;Betta spp.&#x201d; only Betta in italics and &#x201c;spp.&#x201d; not in italics; and the family name Osphronemidae not in italics. There are many cases of missing italics or inconsistency, and a full-text unified check is recommended.</p>
            <p> 8.&#x00a0;&#x00a0; &#x00a0;There are many spelling and language errors, including but not limited to: criticaly &#x2192; critically, Genome assembljies &#x2192; assemblies, inconsistent spelling such as chlorpharynx / chloropharynx, etc. A comprehensive language check is recommended.</p>
            <p>Is the work clearly and accurately presented and does it cite the current literature?</p>
            <p>Partly</p>
            <p>If applicable, is the statistical analysis and its interpretation appropriate?</p>
            <p>Partly</p>
            <p>Are all the source data underlying the results available to ensure full reproducibility?</p>
            <p>Yes</p>
            <p>Is the study design appropriate and is the work technically sound?</p>
            <p>Partly</p>
            <p>Are the conclusions drawn adequately supported by the results?</p>
            <p>Partly</p>
            <p>Are sufficient details of methods and analysis provided to allow replication by others?</p>
            <p>Partly</p>
            <p>Reviewer Expertise:</p>
            <p>marine biology，genome，fish，genetic，DNA，eDNA</p>
            <p>I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.</p>
        </body>
        <sub-article article-type="response" id="comment16219-461103">
            <front-stub>
                <contrib-group>
                    <contrib contrib-type="author">
                        <name>
                            <surname>Nurhidayat</surname>
                            <given-names>Luthfi</given-names>
                        </name>
                        <aff>Faculty of Biology Universitas Gadjah Mada, Indonesia</aff>
                    </contrib>
                </contrib-group>
                <author-notes>
                    <fn fn-type="conflict">
                        <p>
                            <bold>Competing interests: </bold>We declare that we do not have any competing interest.</p>
                    </fn>
                </author-notes>
                <pub-date pub-type="epub">
                    <day>18</day>
                    <month>5</month>
                    <year>2026</year>
                </pub-date>
            </front-stub>
            <body>
                <p>1.&#x00a0;&#x00a0; &#x00a0;Reference genome&#x2013;guided scaffolding may affect structural and collinearity conclusions. The authors used RagTag together with the Betta splendens reference genome for scaffold construction. This approach is feasible for generating chromosome-scale assemblies, but it may also introduce structural bias to some extent, making the assembly closer to the reference genome structure. The conclusions in the current manuscript such as &#x201c;high collinearity,&#x201d; &#x201c;closer phylogenetic relationships,&#x201d; and &#x201c;highly conserved structure&#x201d; are all based on this scaffolding result; therefore: it is recommended to clearly state the potential limitations of reference-guided scaffolding in the Methods and Discussion; and clarify whether the collinearity analysis was based on the original contigs or the reference-guided scaffolds.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this thoughtful comment. We agree that reference-guided scaffolding may introduce structural bias toward the reference genome and that this limitation should be clearly acknowledged when interpreting large-scale synteny and collinearity patterns.</p>
                <p> In our study, the primary genome assemblies were first generated 
                    <italic>de novo</italic> from Oxford Nanopore long reads. The resulting contigs were subsequently scaffolded using RagTag with the 
                    <italic>Betta splendens</italic> genome as a guide to improve chromosome-scale continuity. We acknowledge that this scaffolding strategy may partially influence large-scale structural organization and therefore could increase apparent similarity to the reference genome.</p>
                <p> To clarify this point, we have revised the Result and Discussion sections to explicitly state the potential limitations associated with reference-guided scaffolding. We also clarified that the collinearity analyses were conducted using annotated protein-coding genes and orthologous gene order on the scaffolded assemblies, rather than direct whole-genome nucleotide alignments. Therefore, the inferred syntenic relationships primarily reflect conservation of gene content and relative gene order rather than exact chromosome-scale structural identity.</p>
                <p> In addition, we have softened the interpretation throughout the Discussion section to avoid overstatement. For example, statements such as &#x201c;significant genome conservation,&#x201d; &#x201c;highly conserved structure,&#x201d; and &#x201c;closer evolutionary relationship&#x201d; were revised to more cautious wording including &#x201c;broadly conserved syntenic patterns,&#x201d; &#x201c;comparatively higher levels of shared gene order,&#x201d; and &#x201c;patterns generally consistent with existing taxonomic relationships.&#x201d; We also now emphasize that the observed collinearity patterns should be interpreted as comparative genomic signals within the context of reference-guided scaffolding, rather than definitive evidence of fully conserved chromosomal architecture.</p>
                <p> Nevertheless, because the assemblies were initially generated 
                    <italic>de novo</italic> and the synteny analysis was based on annotated orthologous genes rather than direct reference-guided genome alignment, we believe the analyses still provide informative comparative insights into genome organization among the examined 
                    <italic>Betta</italic> species.</p>
                <p> </p>
                <p> 2.&#x00a0;&#x00a0; &#x00a0;The sample size is limited, and over-inference at the species level should be avoided. The morphological analysis includes only three individuals per species, and genome sequencing includes only one individual per species. This is acceptable for a resource-type paper, but inferences in the following aspects should be more cautious: patterns of interspecific differences; gene duplication dynamics; specific gene insertion events; and inference of evolutionary divergence time.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this important comment. We agree that the limited sample size, particularly the use of a single sequenced individual per species, requires cautious interpretation of species-level inferences. Our primary objective in this study was to generate foundational genomic resources for these threatened 
                    <italic>Betta</italic> species rather than to make definitive population-level evolutionary conclusions.</p>
                <p> In response, we revised the manuscript to avoid overinterpretation by moderating statements related to interspecific differences, gene duplication patterns, insertion events, and evolutionary divergence. We replaced overly definitive wording with more cautious expressions such as &#x201c;is consistent with,&#x201d; &#x201c;may represent,&#x201d; or &#x201c;suggests potential variation,&#x201d; where appropriate.</p>
                <p> We also added statements in the last paragraph of Discussion acknowledging that the assemblies represent single individuals and therefore may not capture the full extent of intraspecific genomic variation. Similarly, we noted that the limited number of specimens used for morphological analyses constrains broader species-level interpretations. However, we note that the examined 
                    <italic>Betta</italic> species are highly endemic and threatened taxa, making specimen collection ethically and logistically challenging. Within this context, the use of three specimens per species for morphological analyses and one individual per species for reference genome generation is consistent with many genomic resource studies involving rare or endangered organisms.</p>
                <p> We believe these revisions provide a more balanced interpretation while preserving the value of the genomic resources presented in this study.</p>
                <p> </p>
                <p> 3.&#x00a0;&#x00a0; &#x00a0;The two &#x201c;large insertions&#x201d; in CSF1RA require stronger supporting evidence. The manuscript reports that CSF1RA in B. burdigala contains two large amino-acid insertions and speculates that they may affect pigment regulation. This result has potential novelty but currently lacks the following validation: long-read coverage; read-level support at the insertion boundaries; whether there are low-complexity or repetitive-sequence artifacts; and whether assembly or annotation errors have been excluded.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this important suggestion. To validate the inferred insertion identified from the gene model, we mapped Oxford Nanopore long reads back to the assembled genome. Coverage analysis revealed consistent read depth across the insertion locus (~70&#x2013;88&#x00d7;), with no evidence of local coverage collapse or assembly breakpoints, thereby supporting the authenticity of the insertion. In addition, long-read alignments spanning the insertion region were visually inspected using Integrative Genomics Viewer and have been included in the Supplementary Materials deposited in figshare (DOI: https://doi.org/10.6084/m9.figshare.31189546.v3 ). The following supplementary materials have been added:</p>
                <p> Supplementary Figure S3. Validation of the CSF1R1 insertion using Oxford Nanopore long-read alignments. Coverage depth across the insertion locus remained consistent (~70&#x2013;88&#x00d7;), and multiple long reads continuously spanned the insertion region, supporting the authenticity of the predicted insertion and excluding local assembly artifacts.</p>
                <p> Supplementary File S4. Coverage depth of the CSF1R1_1 region based on Oxford Nanopore long-read alignments.</p>
                <p> </p>
                <p> 4.&#x00a0;&#x00a0; &#x00a0;Evidence from a single-gene phylogenetic analysis is limited. The authors constructed a phylogenetic tree using the single gene CSF1RA and compared it with the NCBI taxonomy tree. A single-gene tree can only serve as a consistency check and cannot provide strong support for phylogenetic relationships.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this valuable comment. We agree that phylogenetic inference based on a single gene has limited power for resolving species-level evolutionary relationships and should not be interpreted as definitive phylogenetic evidence. In our study, the CSF1RA phylogeny was intended primarily as a gene-level comparative analysis and a consistency check against the established taxonomy, rather than as a comprehensive reconstruction of species relationships. To avoid overinterpretation, we have revised the relevant sections of the manuscript to clarify the purpose and limitations of the single-gene analysis. We now explicitly state that the CSF1RA tree is presented to illustrate evolutionary conservation and relative clustering patterns among related taxa, whereas accepted species relationships remain based on established taxonomy and previous phylogenomic studies.</p>
                <p> In the Results section, we revised the sentence:</p>
                <p> &#x201c;We found that the CSF1RA phylogenetic tree closely resembles the phylogenetic tree of the nine fish species compared based on NCBI taxonomic data&#x201d;</p>
                <p> to:</p>
                <p> &#x201c;Gene-based phylogenetic analyses showed that the CSF1RA tree exhibited clustering patterns broadly consistent with the established taxonomic relationships among the nine fish species based on NCBI taxonomy.&#x201d;</p>
                <p> We also added the following statement to the Results section:</p>
                <p> &#x201c;We note that these analyses are based on single genes and therefore are intended primarily for comparative assessment of gene-level evolutionary patterns rather than for robust species-level phylogenetic inference.&#x201d;</p>
                <p> In addition, we revised the Discussion section to reduce overinterpretation of the single-gene phylogenetic analyses and to present the evolutionary implications more cautiously.</p>
                <p> </p>
                <p> 5.&#x00a0;&#x00a0; &#x00a0;Genome quality assessment metrics can still be strengthened. The manuscript reports N50, scaffold number, BUSCO, GC content, and gap percentage; these metrics are relatively basic. It is recommended to add sequencing depth (estimated coverage); read length N50 or mean read length; k-mer completeness analysis; assembly quality value (QV); and contamination detection methods (if any). Adding 2&#x2013;3 of the above metrics can significantly improve confidence in the assembly.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this valuable suggestion. We agree that including additional assembly quality metrics would strengthen confidence in the genome assemblies. In response, we have revised the manuscript to incorporate additional sequencing and quality-control information.</p>
                <p> First, we updated the 
                    <italic>Genomic DNA extraction and sequencing</italic> subsection in the Methods section. The original text:</p>
                <p> &#x201c;The genome sequence data for 
                    <italic>Betta burdigala</italic> includes 16.38 million reads and 37.39 gigabases. For 
                    <italic>Betta chloropharynx</italic>, the data comprises 14.97 million reads and 57.97 gigabases. Meanwhile, 
                    <italic>Betta schalleri</italic> has 11.83 million reads and 23.75 gigabases.&#x201d;</p>
                <p> has been revised to:</p>
                <p> &#x201c;The genome sequence data for 
                    <italic>Betta burdigala</italic> comprised 16.38 million reads totaling 37.39 Gb, with a read N50 of 5.23 kb, corresponding to an estimated genome coverage of approximately 74.8&#x2013;83.1&#x00d7; assuming a genome size of 450&#x2013;500 Mb. For 
                    <italic>Betta chloropharynx</italic>, sequencing generated 14.97 million reads totaling 57.97 Gb, with a read N50 of 7.75 kb, representing an estimated coverage of approximately 115.9&#x2013;128.8&#x00d7;. Meanwhile, 
                    <italic>Betta schalleri</italic> produced 11.83 million reads totaling 23.75 Gb, with a read N50 of 5.5 kb, corresponding to an estimated genome coverage of approximately 47.5&#x2013;52.8&#x00d7;.&#x201d;</p>
                <p> These additions provide both sequencing depth estimates and read-length statistics requested by the reviewer.</p>
                <p> Second, we updated the 
                    <italic>Genome assembly and annotation</italic> subsection to include contamination screening and preprocessing procedures that were inadvertently omitted from the original manuscript. Specifically, we added the following statements:</p>
                <p> &#x201c;Adapter contamination screening was performed using Porechop_ABI prior to assembly.&#x201d;</p>
                <p> &#x201c;Foreign contamination was screened and removed using NCBI FCS-GX prior to scaffolding.&#x201d;</p>
                <p> Finally, we also incorporated the 21-mer&#x2013;based genome size estimation analysis into the revised Figure 3, which provides an additional k-mer&#x2013;based assessment supporting assembly completeness and consistency with the final assembly sizes.</p>
                <p> 6.&#x00a0;&#x00a0; &#x00a0;The background statements in the Introduction needs revision. There are unclear and illogical sentences in the Introduction, such as the description of &#x201c;16 years&#x201d; and &#x201c;2 species in Thailand and 9 species in Indonesia,&#x201d; which is confusing. Rewrite the relevant paragraphs to make the logic clearer; describe more accurately recent progress in taxonomy and diversity research of the genus Betta; and standardize IUCN status as &#x201c;Critically Endangered (CR)&#x201d; or &#x201c;Endangered (EN)&#x201d; with clear citations.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for the suggestion. We have revised the statement:</p>
                <p> &#x201c;The number of endemic wild Betta distribution and diversity of Southeast Asia has been identified for 16 years in Thailand (2 species) and Indonesia (9 species) 
                    <sup>1-5</sup>&#x201d;</p>
                <p> to</p>
                <p> &#x201c;Indonesia harbors nine wild Betta species classified as critically endangered and seven species categorized as endangered
                    <sup>1-3</sup>. In comparison, Thailand contains two critically endangered wild Betta species and one endangered species
                    <sup>4,5</sup>.&#x201d;</p>
                <p> </p>
                <p> 7.&#x00a0;&#x00a0; &#x00a0;The Latin name format is not standardized. The manuscript should be unified: genus and species names in italics, such as Betta burdigala; abbreviated form B. burdigala; in &#x201c;Betta spp.&#x201d; only Betta in italics and &#x201c;spp.&#x201d; not in italics; and the family name Osphronemidae not in italics. There are many cases of missing italics or inconsistency, and a full-text unified check is recommended.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for this valuable comment, and we apologize for the inconsistencies in the formatting of scientific names throughout the original manuscript. We agree that standardized formatting of Latin names is important for taxonomic clarity and overall manuscript readability.</p>
                <p> In response, we conducted a full-text review of the manuscript to standardize the formatting of scientific names throughout the text, figures, tables, and supplementary materials. Genus and species names are now consistently italicized (e.g., 
                    <italic>Betta burdigala</italic>), abbreviated species names are formatted correctly (e.g., 
                    <italic>B.</italic> burdigala), and in expressions such as 
                    <italic>Betta</italic> spp., only the genus name is italicized while &#x201c;spp.&#x201d; remains in standard font. In addition, family names such as Osphronemidae are now consistently presented in non-italicized format.</p>
                <p> We also corrected multiple instances of missing italics and formatting inconsistencies throughout the manuscript to ensure conformity with standard zoological nomenclature conventions.</p>
                <p> </p>
                <p> </p>
                <p> 8.&#x00a0;&#x00a0; &#x00a0;There are many spelling and language errors, including but not limited to: criticaly &#x2192; critically, Genome assembljies &#x2192; assemblies, inconsistent spelling such as chlorpharynx / chloropharynx, etc. A comprehensive language check is recommended.</p>
                <p> 
                    <bold>Response:</bold>
                </p>
                <p> Thank you for pointing this out. We appreciate the reviewer&#x2019;s careful reading of the manuscript. In response, we conducted a comprehensive language and spelling revision throughout the manuscript to correct typographical errors, improve grammar, and ensure consistency in terminology and species names.</p>
                <p> Specifically, spelling errors such as &#x201c;criticaly&#x201d; to &#x201c;critically,&#x201d; &#x201c;Genome assembljies&#x201d; to &#x201c;genome assemblies,&#x201d; and inconsistent species naming (e.g., &#x201c;chlorpharynx&#x201d; to &#x201c;chloropharynx&#x201d;) were corrected throughout the text. We also carefully reviewed formatting consistency, including the standardized use of italicization for scientific names.</p>
            </body>
        </sub-article>
    </sub-article>
</article>
