# Threadfin

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Family of ray-finned fishes

Threadfin Atlantic threadfin, Polydactylus octonemus Scientific classification Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Carangiformes Suborder: Pleuronectoidei Family: Polynemidae Rafinesque, 1815[1] Genera See text

**Threadfins** are silvery grey [ray-finned fish](/source/Ray-finned_fish) of the [family](/source/Family_(taxonomy)) **Polynemidae**. Found in tropical to subtropical waters throughout the world, the threadfin family contains nine [genera](/source/Genera) and about 40 [species](/source/Species).[2] A distantly related species sometimes known by the name threadfin, *Scyris indica*, is properly the [Indian threadfish](/source/Indian_threadfish) (family [Carangidae](/source/Carangidae)).

Ranging in length from 11 cm (4.5 in) in the [dwarf threadfin](/source/Dwarf_threadfin) (*Parapolynemus verekeri*) to 2 m (6.6 ft) in [fourfinger threadfin](/source/Fourfinger_threadfin) (*Eleutheronema tetradactylum*) and [giant African threadfin](/source/Giant_African_threadfin) (*Polydactylus quadrifilis*), threadfins are both important to commercial [fisheries](/source/Fishery) as a food fish, and popular among [anglers](/source/Fishing). Their habit of forming large schools makes the threadfins a reliable and economic catch.

## Description

Their bodies are [elongated](/source/Ichthyology_terms#E) and [fusiform](/source/Ichthyology_terms#F), with [spinous](/source/Ichthyology_terms#S) and soft [dorsal fins](/source/Dorsal_fin) widely separated. Their tail fins are large and deeply forked, indicating speed and agility. The mouth is large and [inferior](/source/Ichthyology_terms#I); a blunt snout projects far ahead. The jaws and palate possess bands of [villiform](/source/Ichthyology_terms#V) (fibrous) teeth. Their most distinguishing feature is their [pectoral fins](/source/Fish_anatomy#Fins): they are composed of two distinct sections, the lower of which consists of three to seven long, thread-like independent rays. *Polynemus* species may have up to 15 of these modified rays.

 *Filistriatus sexfilis* or *moi* (sixfinger threadfins),[3] were reserved for Hawaiian royalty or the [aliʻi](/source/Ali%CA%BBi).[4]

In some species, such as the royal threadfin (*[Pentanemus quinquarius](/source/Pentanemus_quinquarius)*), 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 [Greek](/source/Greek_language) *poly* meaning "many" and *nema* meaning "filament." Similar species, such as the [mullets](/source/Mullet_(fish)) (family [Mugilidae](/source/Mugilidae)) and [milkfish](/source/Milkfish) (family [Chanidae](/source/Chanidae)), can be easily distinguished from threadfins by their lack of filamentous [pectoral rays](/source/Fish_anatomy#Fins).

## Distribution and habitat

Threadfins frequent open, shallow water in areas with muddy, sandy, or silty bottoms; they are rarely seen at [reefs](/source/Reef). Their pectoral rays are thought to serve as tactile structures, helping to find prey within the [sediments](/source/Sediment). Noted for being [euryhaline](/source/Euryhaline), threadfins can tolerate a wide range of [salinity](/source/Salinity) levels. This attribute allows threadfins to enter [estuaries](/source/Estuary) and even [rivers](/source/River). They feed primarily on [crustaceans](/source/Crustacea) and smaller fish.

## Reproduction

Presumed to be [pelagic](/source/Ichthyology_terms#P) spawners, threadfins probably release many tiny, buoyant eggs into the water column, which then become part of the [plankton](/source/Plankton). The eggs float freely with the currents until hatching.

## Cuisine

Threadfin has been used to create [crab stick](/source/Crab_stick).

## Mariculture

In [Hawaii](/source/Hawaii), sixfinger threadfins are the subject of commercial open-ocean cage [mariculture](/source/Mariculture).[5][6]

## Genera and species

[Fourfinger threadfin](/source/Fourfinger_threadfin) (*Eleutheronema tetradactylum*)

[Sevenfinger threadfin](https://en.wikipedia.org/w/index.php?title=Sevenfinger_threadfin&action=edit&redlink=1) (*Filimanus heptadactyla*)

[Elegant paradise fish](/source/Elegant_paradise_fish) (*Polynemus multifilis*)

The family includes 43 species in nine[7] genera:

- Genus *[Eleutheronema](/source/Eleutheronema)* - *[Eleutheronema rhadinum](https://en.wikipedia.org/w/index.php?title=Eleutheronema_rhadinum&action=edit&redlink=1)* ([Jordan](/source/David_Starr_Jordan) & [Evermann](/source/Barton_Warren_Evermann), 1902) (East Asian fourfinger threadfin) - *[Eleutheronema tetradactylum](/source/Eleutheronema_tetradactylum)* (Shaw, 1804) (Fourfinger threadfin) - *[Eleutheronema tridactylum](https://en.wikipedia.org/w/index.php?title=Eleutheronema_tridactylum&action=edit&redlink=1)* ([Bleeker](/source/Pieter_Bleeker), 1849) (Threefinger threadfin)

- Genus *[Filimanus](/source/Filimanus)* - *[Filimanus heptadactyla](https://en.wikipedia.org/w/index.php?title=Filimanus_heptadactyla&action=edit&redlink=1)* ([Cuvier](/source/Georges_Cuvier), 1829) (Sevenfinger threadfin) - *[Filimanus hexanema](https://en.wikipedia.org/w/index.php?title=Filimanus_hexanema&action=edit&redlink=1)* (Cuvier 1829) (Javanese threadfin) - *[Filimanus perplexa](https://en.wikipedia.org/w/index.php?title=Filimanus_perplexa&action=edit&redlink=1)* Feltes 1991 (Splendid threadfin) - *[Filimanus sealei](https://en.wikipedia.org/w/index.php?title=Filimanus_sealei&action=edit&redlink=1)* ([Jordan](/source/David_Starr_Jordan) & [Richardson](/source/Robert_Earl_Richardson), 1910) (Eightfinger threadfin) - *[Filimanus similis](https://en.wikipedia.org/w/index.php?title=Filimanus_similis&action=edit&redlink=1)* Feltes 1991 (Indian sevenfinger threadfin) - *[Filimanus xanthonema](https://en.wikipedia.org/w/index.php?title=Filimanus_xanthonema&action=edit&redlink=1)* ([Valenciennes](/source/Achille_Valenciennes), 1831) (Yellowthread threadfin)

- Genus *[Filistriatus](/source/Filistriatus)*[7] - *[Filistriatus bifurcus](https://en.wikipedia.org/w/index.php?title=Filistriatus_bifurcus&action=edit&redlink=1)* ([Motomura](/source/Hiroyuki_Motomura), [Kimura](https://en.wikipedia.org/w/index.php?title=Seishi_Kimura&action=edit&redlink=1) & [Iwatsuki](https://en.wikipedia.org/w/index.php?title=Yukio_Iwatsuki&action=edit&redlink=1), 2001) (Slender fivefinger threadfin) - *[Filistriatus plebeius](/source/Filistriatus_plebeius)* ([Broussonet](/source/Pierre_Marie_Auguste_Broussonet), 1782) (Striped threadfin) - *[Filistriatus sexfilis](/source/Filistriatus_sexfilis)* ([Valenciennes](/source/Achille_Valenciennes), 1831) (Sixfinger threadfin) - *[Filistriatus siamensis](https://en.wikipedia.org/w/index.php?title=Filistriatus_siamensis&action=edit&redlink=1)* (Motomura, Iwatsuki & [Yoshino](https://en.wikipedia.org/w/index.php?title=Tetsue_Yoshino&action=edit&redlink=1), 2001) (Largemouth striped threadfin)

- Genus *[Galeoides](/source/Galeoides)* - *[Galeoides decadactylus](/source/Galeoides_decadactylus)* ([Bloch](/source/Marcus_Elieser_Bloch), 1795) ([Lesser African threadfin](/source/Lesser_African_threadfin))

- Genus *[Leptomelanosoma](/source/Leptomelanosoma)* - *[Leptomelanosoma indicum](/source/Leptomelanosoma_indicum)* (Shaw, 1804) ([Indian threadfin](/source/Indian_threadfin)) - *[Leptomelanosoma longipes](https://en.wikipedia.org/w/index.php?title=Polydactylus_longipes&action=edit&redlink=1)* (Motomura, Okamoto & Iwatsuki, 2001) (Long-limb threadfin)

- Genus *[Parapolynemus](/source/Parapolynemus)* - *[Parapolynemus verekeri](/source/Parapolynemus_verekeri)* ([Saville-Kent](/source/William_Saville-Kent), 1889) ([Dwarf paradise fish](/source/Dwarf_paradise_fish))

- Genus *[Pentanemus](/source/Pentanemus)* - *[Pentanemus quinquarius](/source/Pentanemus_quinquarius)* ([Linnaeus](/source/Carl_Linnaeus), [1758](/source/10th_edition_of_Systema_Naturae)) ([Royal threadfin](/source/Royal_threadfin))

- Genus *[Polydactylus](/source/Polydactylus)* (likely not monophyletic[8]) - *[Polydactylus approximans](https://en.wikipedia.org/w/index.php?title=Polydactylus_approximans&action=edit&redlink=1)* ([Lay](/source/George_Tradescant_Lay) & [Bennett](/source/Edward_Turner_Bennett), 1839) (Blue bobo) - *[Polydactylus luparensis](https://en.wikipedia.org/w/index.php?title=Polydactylus_luparensis&action=edit&redlink=1)* [Lim](https://en.wikipedia.org/w/index.php?title=Pek_Khiok_Annie_Lim&action=edit&redlink=1), Motomura & [Gambang](https://en.wikipedia.org/w/index.php?title=Albert_Chuan_Gambag&action=edit&redlink=1), 2010 (Sarawak giant threadfin) - *[Polydactylus macrochir](/source/Polydactylus_macrochir)* ([Günther](/source/Albert_G%C3%BCnther), 1867) ([King threadfin](/source/King_threadfin)) - *[Polydactylus macrophthalmus](https://en.wikipedia.org/w/index.php?title=Polydactylus_macrophthalmus&action=edit&redlink=1)* ([Bleeker](/source/Pieter_Bleeker), 1858) (River threadfin) - *[Polydactylus malagasyensis](https://en.wikipedia.org/w/index.php?title=Polydactylus_malagasyensis&action=edit&redlink=1)* Motomura & Iwatsuki, 2001 (African blackspot threadfin) - *[Polydactylus microstomus](https://en.wikipedia.org/w/index.php?title=Polydactylus_microstomus&action=edit&redlink=1)* ([Bleeker](/source/Pieter_Bleeker), 1851) (Smallmouth threadfin) - *[Polydactylus mullani](https://en.wikipedia.org/w/index.php?title=Polydactylus_mullani&action=edit&redlink=1)* (Hora, 1926) (Arabian blackspot threadfin) - *[Polydactylus multiradiatus](https://en.wikipedia.org/w/index.php?title=Polydactylus_multiradiatus&action=edit&redlink=1)* ([Günther](/source/Albert_G%C3%BCnther), 1860) (Australian threadfin) - *[Polydactylus nigripinnis](https://en.wikipedia.org/w/index.php?title=Polydactylus_nigripinnis&action=edit&redlink=1)* [Munro](/source/Ian_Stafford_Ross_Munro), 1964 (Blackfin threadfin) - *[Polydactylus octonemus](/source/Polydactylus_octonemus)* ([Girard](/source/Charles_Fr%C3%A9d%C3%A9ric_Girard), 1858) (Atlantic threadfin) - *[Polydactylus oligodon](https://en.wikipedia.org/w/index.php?title=Polydactylus_oligodon&action=edit&redlink=1)* ([Günther](/source/Albert_G%C3%BCnther), 1860) (Littlescale threadfin) - *[Polydactylus opercularis](https://en.wikipedia.org/w/index.php?title=Polydactylus_opercularis&action=edit&redlink=1)* [Seale](/source/Alvin_Seale) & [Bean](/source/Barton_Appler_Bean), 1907 (Yellow bobo) - *[Polydactylus persicus](https://en.wikipedia.org/w/index.php?title=Polydactylus_persicus&action=edit&redlink=1)* Motomura & Iwatsuki, 2001 (Persian blackspot threadfin) - *[Polydactylus quadrifilis](/source/Polydactylus_quadrifilis)* ([Cuvier](/source/Georges_Cuvier), 1829) (Giant African threadfin) - *[Polydactylus sextarius](/source/Polydactylus_sextarius)* ([Bloch](/source/Marcus_Elieser_Bloch) & [Schneider](/source/Johann_Gottlob_Schneider), 1801) (Blackspot threadfin) - *[Polydactylus virginicus](https://en.wikipedia.org/w/index.php?title=Polydactylus_virginicus&action=edit&redlink=1)* ([Linnaeus](/source/Carl_Linnaeus), [1758](/source/10th_edition_of_Systema_Naturae)) (Barbu)

- Genus *[Polynemus](/source/Polynemus)* - *[Polynemus aquilonaris](/source/Polynemus_aquilonaris)* Motomura, 2003 ([Northern paradise fish](/source/Northern_paradise_fish)) - *[Polynemus bidentatus](https://en.wikipedia.org/w/index.php?title=Polynemus_bidentatus&action=edit&redlink=1)* Motomura & Tsukawaki, 2006 - *[Polynemus dubius](https://en.wikipedia.org/w/index.php?title=Polynemus_dubius&action=edit&redlink=1)* [Bleeker](/source/Pieter_Bleeker), 1854 ([Eastern paradise fish](https://en.wikipedia.org/w/index.php?title=Eastern_paradise_fish&action=edit&redlink=1)) - *[Polynemus hornadayi](https://en.wikipedia.org/w/index.php?title=Polynemus_hornadayi&action=edit&redlink=1)* [Myers](/source/George_S._Myers), 1936 ([Hornaday's paradise fish](https://en.wikipedia.org/w/index.php?title=Hornaday%27s_paradise_fish&action=edit&redlink=1)) - *[Polynemus kapuasensis](https://en.wikipedia.org/w/index.php?title=Polynemus_kapuasensis&action=edit&redlink=1)* Motomura & [van Oijen](https://en.wikipedia.org/w/index.php?title=Martien_JP_van_Oijen&action=edit&redlink=1), 2003 ([Kapuas elegant paradise fish](https://en.wikipedia.org/w/index.php?title=Kapuas_elegant_paradise_fish&action=edit&redlink=1)) - *[Polynemus melanochir](https://en.wikipedia.org/w/index.php?title=Polynemus_melanochir&action=edit&redlink=1)* [Valenciennes](/source/Achille_Valenciennes), 1831 ([Blackhand paradise fish](https://en.wikipedia.org/w/index.php?title=Blackhand_paradise_fish&action=edit&redlink=1)) - *[Polynemus multifilis](/source/Polynemus_multifilis)* [Temminck](/source/Coenraad_Jacob_Temminck) & [Schlegel](/source/Hermann_Schlegel), 1843 ([Elegant paradise fish](/source/Elegant_paradise_fish)) - *[Polynemus paradiseus](/source/Polynemus_paradiseus)* [Linnaeus](/source/Carl_Linnaeus), [1758](/source/10th_edition_of_Systema_Naturae) ([Paradise threadfin](/source/Paradise_threadfin))

## Phylogeny

The following [cladogram](/source/Cladogram) is from Girard & Chovanec (2025):[7]

Polynemidae "Polydactylus" quadrifilis Pentanemus quinquarius Galeoides decadactylus Polydactylus opercularis Polydactylus approximans Polydactylus virginicus Polydactylus octonemus Polydactylus oligodon Parapolynemus verekeri "Polydactylus" macrochir "Polydactylus" multiradiatus "Polydactylus" nigripinnis Eleutheronema rhadinum Eleutheronema tetradactylum Filistriatus bifurcus Filistriatus plebeius Filistriatus sexfilis Polynemus multifilis Polynemus aquilonaris Polynemus melanochir Polynemus paradiseus Leptomelanosoma indicum Leptomelanosoma macrophthalmus Filimanus perplexa Filimanus similis Filimanus sealei Filimanus xanthonema "Polydactylus" longipes "Polydactylus" mullani "Polydactylus" microstomus "Polydactylus" malagasyensis "Polydactylus" sextarius

## Timeline of genera

## References

1. **[^](#cite_ref-VDLEF_1-0)** Richard van der Laan; William N. Eschmeyer & Ronald Fricke (2014). ["Family-group names of Recent fishes"](https://biotaxa.org/Zootaxa/article/view/zootaxa.3882.1.1/10480). *Zootaxa*. **3882** (2): 001–230. [doi](/source/Doi_(identifier)):[10.11646/zootaxa.3882.1.1](https://doi.org/10.11646%2Fzootaxa.3882.1.1). [PMID](/source/PMID_(identifier)) [25543675](https://pubmed.ncbi.nlm.nih.gov/25543675).

1. **[^](#cite_ref-Nelson5errata_2-0)** ["Inserts for pages 437–441"](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) (PDF). John Wiley & Sons Limited. Retrieved 13 April 2020.

1. **[^](#cite_ref-3)** [Froese, Rainer](/source/Rainer_Froese); [Pauly, Daniel](/source/Daniel_Pauly) (eds.). ["*Polydactylus sexfilis*"](https://www.fishbase.org/summary/SpeciesSummary.php?genusname=Polydactylus&speciesname=sexfilis). *[FishBase](/source/FishBase)*. August 2019 version.

1. **[^](#cite_ref-krisnawati&umemoto_4-0)** Suryanata, Krisnawati; Umemoto, Karen N. (2005). "Tension at the nexus of the global and local: culture, property, and marine aquaculture in Hawaiʻi". *Environment and Planning A*. **35** (2): 199, 206. [CiteSeerX](/source/CiteSeerX_(identifier)) [10.1.1.456.680](https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.456.680). [doi](/source/Doi_(identifier)):[10.1068/a35116](https://doi.org/10.1068%2Fa35116). [S2CID](/source/S2CID_(identifier)) [143928957](https://api.semanticscholar.org/CorpusID:143928957).

1. **[^](#cite_ref-5)** Lin, DT; Bailey-Brock, JH (2008). ["Partial recovery of infaunal communities during a fallow period at an open-ocean aquaculture"](https://www.int-res.com/abstracts/meps/v371/p65-72/). *Marine Ecology Progress Series*. **371**: 65–72. [Bibcode](/source/Bibcode_(identifier)):[2008MEPS..371...65L](https://ui.adsabs.harvard.edu/abs/2008MEPS..371...65L). [doi](/source/Doi_(identifier)):[10.3354/meps07675](https://doi.org/10.3354%2Fmeps07675).

1. **[^](#cite_ref-6)** Lee, HW; Bailey-Brock, JH; McGurr, MM (2006). ["Temporal changes in the polychaete infaunal community surrounding a Hawaiian mariculture operation"](https://www.int-res.com/abstracts/meps/v307/p175-185/). *Marine Ecology Progress Series*. **307**: 175–185. [Bibcode](/source/Bibcode_(identifier)):[2006MEPS..307..175L](https://ui.adsabs.harvard.edu/abs/2006MEPS..307..175L). [doi](/source/Doi_(identifier)):[10.3354/meps307175](https://doi.org/10.3354%2Fmeps307175).

1. ^ [***a***](#cite_ref-:0_7-0) [***b***](#cite_ref-:0_7-1) [***c***](#cite_ref-:0_7-2) Girard, Matthew G.; Chovanec, Kevin R. (2025-09-30). ["Unlocking the genomic potential of historical and formalin-fixed specimens: phylogenetic insights from museum-preserved threadfin fishes (Teleostei: Polynemidae)"](https://peerj.com/articles/20029). *PeerJ*. **13** e20029. [doi](/source/Doi_(identifier)):[10.7717/peerj.20029](https://doi.org/10.7717%2Fpeerj.20029). [ISSN](/source/ISSN_(identifier)) [2167-8359](https://search.worldcat.org/issn/2167-8359).

1. **[^](#cite_ref-8)** 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"](https://onlinelibrary.wiley.com/doi/abs/10.1111/jfb.14997). *Journal of Fish Biology*. **100** (3): 793–810. [Bibcode](/source/Bibcode_(identifier)):[2022JFBio.100..793G](https://ui.adsabs.harvard.edu/abs/2022JFBio.100..793G). [doi](/source/Doi_(identifier)):[10.1111/jfb.14997](https://doi.org/10.1111%2Fjfb.14997). [ISSN](/source/ISSN_(identifier)) [1095-8649](https://search.worldcat.org/issn/1095-8649). [PMID](/source/PMID_(identifier)) [35137410](https://pubmed.ncbi.nlm.nih.gov/35137410). [S2CID](/source/S2CID_(identifier)) [246678758](https://api.semanticscholar.org/CorpusID:246678758).

This article includes a list of general references, but it lacks sufficient corresponding inline citations. Please help to improve this article by introducing more precise citations. (November 2008) (Learn how and when to remove this message)

- [Froese, Rainer](/source/Rainer_Froese); [Pauly, Daniel](/source/Daniel_Pauly) (eds.). ["Family Polynemidae"](https://www.fishbase.org/summary/FamilySummary.php?family=Polynemidae). *[FishBase](/source/FishBase)*. January 2006 version.

- Sepkoski, Jack (2002). ["A compendium of fossil marine animal genera"](https://web.archive.org/web/20090220223520/http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class). *Bulletins of American Paleontology*. **364**: 560. Archived from [the original](http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class) on 2009-02-20. Retrieved 2011-05-19.

## External links

- [Fisheries Western Australia - Threadfins Fact Sheet](http://www.fish.wa.gov.au/About-Us/Publications/Recreational-Fishing/Pages/Fact-Sheets.aspx)

- [The Paradise threadfin, Polynemus paradiseus](https://web.archive.org/web/20040217232857/http://www.practicalfishkeeping.co.uk/pfk/pages/show_article.php?article_id=111)

- [Offshore aquaculture project yields a traditional Hawaiian delicacy](https://web.archive.org/web/20040223170521/http://www.oar.noaa.gov/spotlite/archive/spot_hawaii.html)

Taxon identifiers Polynemidae Wikidata: Q924957 Wikispecies: Polynemidae ADW: Polynemidae AFD: Polynemidae BOLD: 1878 CoL: 627K4 EoL: 5262 GBIF: 8592 iNaturalist: 54192 IRMNG: 114147 ITIS: 170445 NCBI: 30917 Open Tree of Life: 72393 Paleobiology Database: 266163 Plazi: 6A5BAE7A-DA4A-FFD1-3AAA-F9D89D73F905 WoRMS: 125551

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Adapted from the Wikipedia article [Threadfin](https://en.wikipedia.org/wiki/Threadfin) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Threadfin?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.