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Threadfin
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<h2 id="description">Description</h2> <p>Their bodies are <a href="/facts/Ichthyology_terms/KhUc3E6r">elongated</a> and <a href="/facts/Ichthyology_terms/KhUc3E6r">fusiform</a>, with <a href="/facts/Ichthyology_terms/KhUc3E6r">spinous</a> and soft <a href="/facts/Dorsal_fin/zAPuxI1G">dorsal fins</a> widely separated. Their tail fins are large and deeply forked, indicating speed and agility. The mouth is large and <a href="/facts/Ichthyology_terms/KhUc3E6r">inferior</a>; a blunt snout projects far ahead. The jaws and palate possess bands of <a href="/facts/Ichthyology_terms/KhUc3E6r">villiform</a> (fibrous) teeth. Their most distinguishing feature is their <a href="/facts/Fish_anatomy/xyCLgVrB">pectoral fins</a>: they are composed of two distinct sections, the lower of which consists of three to seven long, thread-like independent rays. <i>Polynemus</i> species may have up to 15 of these modified rays. </p> <p>In some species, such as the royal threadfin (<i><a href="/facts/Pentanemus_quinquarius/s9l5DHSM">Pentanemus quinquarius</a></i>), the thread-like rays may extend well past the tail fin. This feature explains both the common name threadfin and the family name Polynemidae, from the <a href="/facts/Greek_language/pzDd6eIz">Greek</a> <i>poly</i> meaning "many" and <i>nema</i> meaning "filament." Similar species, such as the <a href="/facts/Mullet_(fish)/zjEod6Yx">mullets</a> (family <a href="/facts/Mugilidae/zjEod6Yx">Mugilidae</a>) and <a href="/facts/Milkfish/lqD5MX2Q">milkfish</a> (family <a href="/facts/Chanidae/XUla0cwk">Chanidae</a>), can be easily distinguished from threadfins by their lack of filamentous <a href="/facts/Fish_anatomy/xyCLgVrB">pectoral rays</a>. </p> <h2 id="distribution-and-habitat">Distribution and habitat</h2> <p>Threadfins frequent open, shallow water in areas with muddy, sandy, or silty bottoms; they are rarely seen at <a href="/facts/Reef/eHTITdLb">reefs</a>. Their pectoral rays are thought to serve as tactile structures, helping to find prey within the <a href="/facts/Sediment/zsIH1A6U">sediments</a>. Noted for being <a href="/facts/Euryhaline/V39UNHdL">euryhaline</a>, threadfins can tolerate a wide range of <a href="/facts/Salinity/X6mB1YAM">salinity</a> levels. This attribute allows threadfins to enter <a href="/facts/Estuary/WmkSInmK">estuaries</a> and even <a href="/facts/River/GxdjEX21">rivers</a>. They feed primarily on <a href="/facts/Crustacea/PBobIVJP">crustaceans</a> and smaller fish. </p> <h2 id="reproduction">Reproduction</h2> <p>Presumed to be <a href="/facts/Ichthyology_terms/KhUc3E6r">pelagic</a> spawners, threadfins probably release many tiny, buoyant eggs into the water column, which then become part of the <a href="/facts/Plankton/WGo3LU9T">plankton</a>. The eggs float freely with the currents until hatching. </p> <h2 id="cuisine">Cuisine</h2> <p>Threadfin has been used to create <a href="/facts/Crab_stick/MJhWedoH">crab stick</a>. </p> <h2 id="mariculture">Mariculture</h2> <p>In <a href="/facts/Hawaii/ImxFefeK">Hawaii</a>, sixfinger threadfins are the subject of commercial open-ocean cage <a href="/facts/Mariculture/WJYzrKC9">mariculture</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a><a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p> <h2 id="genera-and-species">Genera and species</h2> <p>The family includes 43 species in eight genera: </p> <ul><li>Genus <i><a href="/facts/Eleutheronema/mxH4ugc8">Eleutheronema</a></i> <ul><li><i>Eleutheronema rhadinum</i> (<a href="/facts/David_Starr_Jordan/qLNo5UIR">Jordan</a> & <a href="/facts/Barton_Warren_Evermann/a90t53de">Evermann</a>, 1902) (East Asian fourfinger threadfin)</li> <li><i><a href="/facts/Eleutheronema_tetradactylum/DCkp3dEn">Eleutheronema tetradactylum</a></i> (Shaw, 1804) (Fourfinger threadfin)</li> <li><i>Eleutheronema tridactylum</i> (<a href="/facts/Pieter_Bleeker/Qu3obMnw">Bleeker</a>, 1849) (Threefinger threadfin)</li></ul></li> <li>Genus <i><a href="/facts/Filimanus/w4aqlmkf">Filimanus</a></i> <ul><li><i>Filimanus heptadactyla</i> (<a href="/facts/Georges_Cuvier/4mmE7NzN">Cuvier</a>, 1829) (Sevenfinger threadfin)</li> <li><i>Filimanus hexanema</i> (Cuvier 1829) (Javanese threadfin)</li> <li><i>Filimanus perplexa</i> Feltes 1991 (Splendid threadfin)</li> <li><i>Filimanus sealei</i> (<a href="/facts/David_Starr_Jordan/qLNo5UIR">Jordan</a> & <a href="/facts/Robert_Earl_Richardson/LvKQmpJp">Richardson</a>, 1910) (Eightfinger threadfin)</li> <li><i>Filimanus similis</i> Feltes 1991 (Indian sevenfinger threadfin)</li> <li><i>Filimanus xanthonema</i> (<a href="/facts/Achille_Valenciennes/6Y6VAjA5">Valenciennes</a>, 1831) (Yellowthread threadfin)</li></ul></li> <li>Genus <i><a href="/facts/Galeoides/E0WsDYhz">Galeoides</a></i> <ul><li><i><a href="/facts/Galeoides_decadactylus/E0WsDYhz">Galeoides decadactylus</a></i> (<a href="/facts/Marcus_Elieser_Bloch/QmJ7aoJq">Bloch</a>, 1795) (<a href="/facts/Lesser_African_threadfin/E0WsDYhz">Lesser African threadfin</a>)</li></ul></li> <li>Genus <i><a href="/facts/Leptomelanosoma/EhP4AGGD">Leptomelanosoma</a></i> <ul><li><i><a href="/facts/Leptomelanosoma_indicum/EhP4AGGD">Leptomelanosoma indicum</a></i> (Shaw, 1804) (<a href="/facts/Indian_threadfin/EhP4AGGD">Indian threadfin</a>)</li></ul></li> <li>Genus <i><a href="/facts/Parapolynemus/ShvquClS">Parapolynemus</a></i> <ul><li><i><a href="/facts/Parapolynemus_verekeri/ShvquClS">Parapolynemus verekeri</a></i> (<a href="/facts/William_Saville-Kent/BvEBfJkm">Saville-Kent</a>, 1889) (<a href="/facts/Dwarf_paradise_fish/ShvquClS">Dwarf paradise fish</a>)</li></ul></li> <li>Genus <i><a href="/facts/Pentanemus/s9l5DHSM">Pentanemus</a></i> <ul><li><i><a href="/facts/Pentanemus_quinquarius/s9l5DHSM">Pentanemus quinquarius</a></i> (<a href="/facts/Carl_Linnaeus/gy5HWkHS">Linnaeus</a>, <a href="/facts/10th_edition_of_Systema_Naturae/8H6KJrLJ">1758</a>) (<a href="/facts/Royal_threadfin/s9l5DHSM">Royal threadfin</a>)</li></ul></li> <li>Genus <i><a href="/facts/Polydactylus/eCyasQxp">Polydactylus</a></i> (likely not monophyletic<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>) <ul><li><i>Polydactylus approximans</i> (<a href="/facts/George_Tradescant_Lay/CqI47DdQ">Lay</a> & <a href="/facts/Edward_Turner_Bennett/ncmrCGbG">Bennett</a>, 1839) (Blue bobo)</li> <li><i>Polydactylus bifurcus</i> <a href="/facts/Hiroyuki_Motomura/5XJph6Et">Motomura</a>, Kimura & Iwatsuki, 2001 (Slender fivefinger threadfin)</li> <li><i>Polydactylus longipes</i> Motomura, Okamoto & Iwatsuki, 2001 (Long-limb threadfin)</li> <li><i>Polydactylus luparensis</i> Lim, Motomura & Gambang, 2010 (Sarawak giant threadfin)</li> <li><i><a href="/facts/Polydactylus_macrochir/PTHFrM27">Polydactylus macrochir</a></i> (<a href="/facts/Albert_G%C3%BCnther/SQzexVaS">Günther</a>, 1867) (<a href="/facts/King_threadfin/PTHFrM27">King threadfin</a>)</li> <li><i>Polydactylus macrophthalmus</i> (<a href="/facts/Pieter_Bleeker/Qu3obMnw">Bleeker</a>, 1858) (River threadfin)</li> <li><i>Polydactylus malagasyensis</i> Motomura & Iwatsuki, 2001 (African blackspot threadfin)</li> <li><i>Polydactylus microstomus</i> (<a href="/facts/Pieter_Bleeker/Qu3obMnw">Bleeker</a>, 1851) (Smallmouth threadfin)</li> <li><i>Polydactylus mullani</i> (Hora, 1926) (Arabian blackspot threadfin)</li> <li><i>Polydactylus multiradiatus</i> (<a href="/facts/Albert_G%C3%BCnther/SQzexVaS">Günther</a>, 1860) (Australian threadfin)</li> <li><i>Polydactylus nigripinnis</i> <a href="/facts/Ian_Stafford_Ross_Munro/a5ug3mlF">Munro</a>, 1964 (Blackfin threadfin)</li> <li><i><a href="/facts/Polydactylus_octonemus/LpB3L0b5">Polydactylus octonemus</a></i> (<a href="/facts/Charles_Fr%C3%A9d%C3%A9ric_Girard/1LzxMR7s">Girard</a>, 1858) (Atlantic threadfin)</li> <li><i>Polydactylus oligodon</i> (<a href="/facts/Albert_G%C3%BCnther/SQzexVaS">Günther</a>, 1860) (Littlescale threadfin)</li> <li><i>Polydactylus opercularis</i> <a href="/facts/Alvin_Seale/WF1xNzBA">Seale</a> & <a href="/facts/Barton_Appler_Bean/f0U35dmu">Bean</a>, 1907 (Yellow bobo)</li> <li><i>Polydactylus persicus</i> Motomura & Iwatsuki, 2001 (Persian blackspot threadfin)</li> <li><i><a href="/facts/Polydactylus_plebeius/lJ3gSSw1">Polydactylus plebeius</a></i> (<a href="/facts/Pierre_Marie_Auguste_Broussonet/zMXa0EYr">Broussonet</a>, 1782) (Striped threadfin)</li> <li><i><a href="/facts/Polydactylus_quadrifilis/rehILNn1">Polydactylus quadrifilis</a></i> (<a href="/facts/Georges_Cuvier/4mmE7NzN">Cuvier</a>, 1829) (Giant African threadfin)</li> <li><i><a href="/facts/Polydactylus_sexfilis/ksGQJWG3">Polydactylus sexfilis</a></i> (<a href="/facts/Achille_Valenciennes/6Y6VAjA5">Valenciennes</a>, 1831) (Sixfinger threadfin)</li> <li><i><a href="/facts/Polydactylus_sextarius/80aphLCt">Polydactylus sextarius</a></i> (<a href="/facts/Marcus_Elieser_Bloch/QmJ7aoJq">Bloch</a> & <a href="/facts/Johann_Gottlob_Schneider/jntznJbV">Schneider</a>, 1801) (Blackspot threadfin)</li> <li><i>Polydactylus siamensis</i> Motomura, Iwatsuki & Yoshino, 2001 (Largemouth striped threadfin)</li> <li><i>Polydactylus virginicus</i> (<a href="/facts/Carl_Linnaeus/gy5HWkHS">Linnaeus</a>, <a href="/facts/10th_edition_of_Systema_Naturae/8H6KJrLJ">1758</a>) (Barbu)</li></ul></li> <li>Genus <i><a href="/facts/Polynemus/K9EpUxPI">Polynemus</a></i> <ul><li><i><a href="/facts/Polynemus_aquilonaris/baBHbmlm">Polynemus aquilonaris</a></i> Motomura, 2003 (<a href="/facts/Northern_paradise_fish/baBHbmlm">Northern paradise fish</a>)</li> <li><i>Polynemus bidentatus</i> Motomura & Tsukawaki, 2006</li> <li><i>Polynemus dubius</i> <a href="/facts/Pieter_Bleeker/Qu3obMnw">Bleeker</a>, 1854 (Eastern paradise fish)</li> <li><i>Polynemus hornadayi</i> <a href="/facts/George_S._Myers/k4kxAp8b">Myers</a>, 1936 (Hornaday's paradise fish)</li> <li><i>Polynemus kapuasensis</i> Motomura & van Oijen, 2003 (Kapuas elegant paradise fish)</li> <li><i>Polynemus melanochir</i> <a href="/facts/Achille_Valenciennes/6Y6VAjA5">Valenciennes</a>, 1831 (Blackhand paradise fish)</li> <li><i><a href="/facts/Polynemus_multifilis/a6ckdJyR">Polynemus multifilis</a></i> <a href="/facts/Coenraad_Jacob_Temminck/sDC9WWp5">Temminck</a> & <a href="/facts/Hermann_Schlegel/SuRCpIld">Schlegel</a>, 1843 (<a href="/facts/Elegant_paradise_fish/a6ckdJyR">Elegant paradise fish</a>)</li> <li><i><a href="/facts/Polynemus_paradiseus/JfDX09IG">Polynemus paradiseus</a></i> <a href="/facts/Carl_Linnaeus/gy5HWkHS">Linnaeus</a>, <a href="/facts/10th_edition_of_Systema_Naturae/8H6KJrLJ">1758</a> (<a href="/facts/Paradise_threadfin/JfDX09IG">Paradise threadfin</a>)</li></ul></li></ul> <h2 id="timeline-of-genera">Timeline of genera</h2> <ul><li><a href="/facts/Rainer_Froese/YSvh9csS">Froese, Rainer</a>; <a href="/facts/Daniel_Pauly/0JsBKSFT">Pauly, Daniel</a> (eds.). <a href="http://www.fishbase.org/Summary/FamilySummary.php?family=Polynemidae">"Family Polynemidae"</a>. <i><a href="/facts/FishBase/SMpzPGmF">FishBase</a></i>. January 2006 version.</li> <li>Sepkoski, Jack (2002). <a href="https://web.archive.org/web/20090220223520/http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class">"A compendium of fossil marine animal genera"</a>. <i>Bulletins of American Paleontology</i>. 364: 560. Archived from <a href="http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class">the original</a> on 2009-02-20. Retrieved 2011-05-19.</li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="http://www.fish.wa.gov.au/About-Us/Publications/Recreational-Fishing/Pages/Fact-Sheets.aspx">Fisheries Western Australia - Threadfins Fact Sheet</a></li> <li><a href="https://web.archive.org/web/20040217232857/http://www.practicalfishkeeping.co.uk/pfk/pages/show_article.php?article_id=111">The Paradise threadfin, Polynemus paradiseus</a></li> <li><a href="https://web.archive.org/web/20040223170521/http://www.oar.noaa.gov/spotlite/archive/spot_hawaii.html">Offshore aquaculture project yields a traditional Hawaiian delicacy</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Inserts for pages 437–441" (PDF). John Wiley & Sons Limited. Retrieved 13 April 2020. <a href="https://81a86d48-a-62cb3a1a-s-sites.googlegroups.com/site/fotw5th/Inserts%20for%20pp.%20437-441%20in%20FotW5.pdf?attachauth=ANoY7cru1eiQxyWX8FftCgaTlRq9uD0uYDI1EC32O0iAg-exxLlJoV0tig3JxqIskoE9lDff-FZQgh-HnL2SjOMJcBU3obkvnrkdEJJK-81gj_tCcLedWnb6FgxKVLIY_TGKddKHUVwBuXDEv_JTYPh-mLSQcdVoFfVTHyK-UfvJzknKcwPrwv1Emc1ecKU8OkALrUr6PX_CEHQIjheLBwZ3EwOb7kqz8iSpmirHBGnnbtpJx1aiszU%3D&attredirects=0" target="_blank">https://81a86d48-a-62cb3a1a-s-sites.googlegroups.com/site/fotw5th/Inserts%20for%20pp.%20437-441%20in%20FotW5.pdf?attachauth=ANoY7cru1eiQxyWX8FftCgaTlRq9uD0uYDI1EC32O0iAg-exxLlJoV0tig3JxqIskoE9lDff-FZQgh-HnL2SjOMJcBU3obkvnrkdEJJK-81gj_tCcLedWnb6FgxKVLIY_TGKddKHUVwBuXDEv_JTYPh-mLSQcdVoFfVTHyK-UfvJzknKcwPrwv1Emc1ecKU8OkALrUr6PX_CEHQIjheLBwZ3EwOb7kqz8iSpmirHBGnnbtpJx1aiszU%3D&attredirects=0</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Lin, DT; Bailey-Brock, JH (2008). "Partial recovery of infaunal communities during a fallow period at an open-ocean aquaculture". Marine Ecology Progress Series. 371: 65–72. Bibcode:2008MEPS..371...65L. doi:10.3354/meps07675. <a href="https://www.int-res.com/abstracts/meps/v371/p65-72/" target="_blank">https://www.int-res.com/abstracts/meps/v371/p65-72/</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Lee, HW; Bailey-Brock, JH; McGurr, MM (2006). "Temporal changes in the polychaete infaunal community surrounding a Hawaiian mariculture operation". Marine Ecology Progress Series. 307: 175–185. Bibcode:2006MEPS..307..175L. doi:10.3354/meps307175. <a href="https://www.int-res.com/abstracts/meps/v307/p175-185/" target="_blank">https://www.int-res.com/abstracts/meps/v307/p175-185/</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Girard, Matthew G.; Davis, Matthew P.; Baldwin, Carole C.; Dettaï, Agnès; Martin, Rene P.; Smith, W. Leo (2022). "Molecular phylogeny of the threadfin fishes (Polynemidae) using ultraconserved elements". Journal of Fish Biology. 100 (3): 793–810. Bibcode:2022JFBio.100..793G. doi:10.1111/jfb.14997. ISSN 1095-8649. PMID 35137410. S2CID 246678758. <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/jfb.14997" target="_blank">https://onlinelibrary.wiley.com/doi/abs/10.1111/jfb.14997</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> </ol>