View source for Threadfin

{{Short description|Family of fishes}}
{{Automatic taxobox
| image = Atlantic threadfin ( Polydactylus octonemus ).jpg
| image_caption = [[Atlantic threadfin]], ''Polydactylus octonemus''
| taxon = Polynemidae
| authority = [[Constantine Samuel Rafinesque|Rafinesque]], 1815<ref name = VDLEF>{{cite journal | author1 = Richard van der Laan | author2 = William N. Eschmeyer | author3 = Ronald Fricke | name-list-style = amp |year=2014 | title = Family-group names of Recent fishes | url = https://biotaxa.org/Zootaxa/article/view/zootaxa.3882.1.1/10480 | journal = Zootaxa | volume = 3882 | issue =2 | pages = 001–230| doi = 10.11646/zootaxa.3882.1.1 | pmid = 25543675 | doi-access = free }}</ref>
| subdivision_ranks = Genera
| subdivision = See text
}}

'''Threadfins''' are silvery grey [[fish]] of the [[Family (biology)|family]] '''Polynemidae''', taxonomically considered a type of [[flatfish]]. Found in tropical to subtropical waters throughout the world, the threadfin family contains nine [[genera]] and about 40 [[species]].<ref name = Nelson5errata>{{cite web | url = 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 | title = Inserts for pages 437–441 | access-date = 13 April 2020 | publisher = John Wiley & Sons Limited}}</ref> An unrelated species sometimes known by the name threadfin, ''Alectis indicus'', is properly the [[Indian threadfish]] (family [[Carangidae]]).

Ranging in length from {{convert|11|cm|in|abbr=on|round=0.5}} in the [[dwarf threadfin]] (''Parapolynemus verekeri'') to {{convert|2|m|ft|abbr=on}} in [[fourfinger threadfin]] (''Eleutheronema tetradactylum'') and [[giant African threadfin]] (''Polydactylus quadrifilis''), threadfins are both important to commercial [[fishery|fisheries]] as a food fish, and popular among [[fishing|angler]]s. Their habit of forming large schools makes the threadfins a reliable and economic catch.

==Description==
Their bodies are [[Ichthyology terms#E|elongated]] and [[Ichthyology terms#F|fusiform]], with [[Ichthyology terms#S|spinous]] and soft [[dorsal fin]]s widely separated. Their tail fins are large and deeply forked, indicating speed and agility. The mouth is large and [[Ichthyology terms#I|inferior]]; a blunt snout projects far ahead. The jaws and palate possess bands of [[Ichthyology terms#V|villiform]] (fibrous) teeth. Their most distinguishing feature is their [[Fish anatomy#Fins|pectoral 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.

[[Image:sixfinger threadfin school.jpg|thumb|left|200px| ''Polydactylus sexfilis'' or ''moi'' (sixfinger threadfins),<ref>{{FishBase |genus=Polydactylus |species=sexfilis  |id= |month=August |year=2019 }}</ref> were reserved for Hawaiian royalty or the [[aliʻi]]<!--ali'i-->.<ref name=krisnawati&umemoto/>]]

In some species, such as the royal threadfin (''[[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 language|Greek]] ''poly'' meaning "many" and ''nema'' meaning "filament." Similar species, such as the [[mullet (fish)|mullets]] (family [[Mugilidae]]) and [[milkfish]] (family [[Chanidae]]), can be easily distinguished from threadfins by their lack of filamentous [[Fish anatomy#Fins|pectoral rays]].

==Distribution and habitat==
Threadfins frequent open, shallow water in areas with muddy, sandy, or silty bottoms; they are rarely seen at [[reef]]s. Their pectoral rays are thought to serve as tactile structures, helping to find prey within the [[sediment]]s. Noted for being [[euryhaline]], threadfins can tolerate a wide range of [[salinity]] levels. This attribute allows threadfins to enter [[estuary|estuaries]] and even [[river]]s. They feed primarily on [[crustacea]]ns and smaller fish.

==Reproduction==
Presumed to be [[Ichthyology terms#P|pelagic]] spawners, threadfins probably release many tiny, buoyant eggs into the water column, which then become part of the [[plankton]]. The eggs float freely with the currents until hatching.

==Cuisine==

Threadfin has been used to create [[crab stick]].

==Mariculture==
In [[Hawaii]], sixfinger threadfins are the subject of commercial open-ocean cage [[mariculture]].<ref>{{Cite journal|url=https://www.int-res.com/abstracts/meps/v371/p65-72/|doi = 10.3354/meps07675|title = Partial recovery of infaunal communities during a fallow period at an open-ocean aquaculture|year = 2008|last1 = Lin|first1 = DT|last2 = Bailey-Brock|first2 = JH|journal = Marine Ecology Progress Series|volume = 371|pages = 65–72|bibcode = 2008MEPS..371...65L|doi-access = free}}</ref><ref>{{Cite journal|url=https://www.int-res.com/abstracts/meps/v307/p175-185/|doi=10.3354/meps307175|title=Temporal changes in the polychaete infaunal community surrounding a Hawaiian mariculture operation|year=2006|last1=Lee|first1=HW|last2=Bailey-Brock|first2=JH|last3=McGurr|first3=MM|journal=Marine Ecology Progress Series|volume=307|pages=175–185|bibcode=2006MEPS..307..175L|doi-access=free}}</ref>

==Genera and species==
[[File:Eleutheronema tetradactylum(Shaw, 1804).jpg|thumb|[[Fourfinger threadfin]] (''Eleutheronema tetradactylum'')]]
[[File:Filimanus heptadactyla.png|thumb|[[Sevenfinger threadfin]] (''Filimanus heptadactyla'')]]
[[File:Elegant paradiseus fish Polynemus multifilis.jpg|thumb|[[Elegant paradise fish]] (''Polynemus multifilis'')]]

The family includes 43 species in nine<ref name=":0">{{Cite journal |last1=Girard |first1=Matthew G. |last2=Chovanec |first2=Kevin R. |date=2025-09-30 |title=Unlocking the genomic potential of historical and formalin-fixed specimens: phylogenetic insights from museum-preserved threadfin fishes (Teleostei: Polynemidae) |url=https://peerj.com/articles/20029 |journal=PeerJ |language=en |volume=13 |article-number=e20029 |doi=10.7717/peerj.20029 |doi-access=free |issn=2167-8359}}</ref> genera:

* Genus ''[[Eleutheronema]]''
** ''[[Eleutheronema rhadinum]]'' <small>([[David Starr Jordan|Jordan]] & [[Barton Warren Evermann|Evermann]], 1902)</small> (East Asian fourfinger threadfin) 
** ''[[Eleutheronema tetradactylum]]'' <small>(Shaw, 1804)</small> (Fourfinger threadfin)
** ''[[Eleutheronema tridactylum]]'' <small>([[Pieter Bleeker|Bleeker]], 1849)</small> (Threefinger threadfin)
* Genus ''[[Filimanus]]''
** ''[[Filimanus heptadactyla]]'' <small>([[Georges Cuvier|Cuvier]], 1829)</small> (Sevenfinger threadfin)
** ''[[Filimanus hexanema]]'' <small>(Cuvier 1829)</small> (Javanese threadfin)
** ''[[Filimanus perplexa]]'' <small>Feltes 1991</small> (Splendid threadfin)
** ''[[Filimanus sealei]]'' <small>([[David Starr Jordan|Jordan]] & [[Robert Earl Richardson|Richardson]], 1910)</small> (Eightfinger threadfin)
** ''[[Filimanus similis]]'' <small>Feltes 1991</small> (Indian sevenfinger threadfin)
** ''[[Filimanus xanthonema]]'' <small>([[Achille Valenciennes|Valenciennes]], 1831)</small> (Yellowthread threadfin)
* Genus ''Filistriatus''<ref name=":0" />
** ''[[Polydactylus bifurcus|Filistriatus bifurcus]]'' (<small>[[Hiroyuki Motomura|Motomura]], [[Seishi Kimura|Kimura]] & [[Yukio Iwatsuki|Iwatsuki]], 2001)</small> (Slender fivefinger threadfin)
** ''[[Polydactylus plebeius|Filistriatus plebeius]]'' <small>([[Pierre Marie Auguste Broussonet|Broussonet]], 1782)</small> (Striped threadfin)
** ''Filistriatus [[Polydactylus sexfilis|sexfilis]]'' <small>([[Achille Valenciennes|Valenciennes]], 1831)</small> (Sixfinger threadfin)
** ''[[Polydactylus siamensis|Filistriatus siamensis]]'' (<small>Motomura, Iwatsuki & [[Tetsue Yoshino|Yoshino]], 2001)</small> (Largemouth striped threadfin)
* Genus ''[[Galeoides]]''
** ''[[Galeoides decadactylus]]'' <small>([[Marcus Elieser Bloch|Bloch]], 1795)</small> ([[Lesser African threadfin]])
* Genus ''[[Leptomelanosoma]]''
** ''[[Leptomelanosoma indicum]]'' <small>(Shaw, 1804)</small> ([[Indian threadfin]])
** ''[[Polydactylus longipes|Leptomelanosoma longipes]]'' (<small>Motomura, Okamoto & Iwatsuki, 2001)</small> (Long-limb threadfin)
* Genus ''[[Parapolynemus]]''
** ''[[Parapolynemus verekeri]]'' <small>([[William Saville-Kent|Saville-Kent]], 1889)</small> ([[Dwarf paradise fish]])
* Genus ''[[Pentanemus]]''
** ''[[Pentanemus quinquarius]]'' <small>([[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]])</small> ([[Royal threadfin]])
* Genus ''[[Polydactylus]]'' (likely not monophyletic<ref>{{Cite journal|last1=Girard|first1=Matthew G.|last2=Davis|first2=Matthew P.|last3=Baldwin|first3=Carole C.|last4=Dettaï|first4=Agnès|last5=Martin|first5=Rene P.|last6=Smith|first6=W. Leo|title=Molecular phylogeny of the threadfin fishes (Polynemidae) using ultraconserved elements|url=https://onlinelibrary.wiley.com/doi/abs/10.1111/jfb.14997|journal=Journal of Fish Biology|year=2022|volume=100|issue=3|pages=793–810|language=en|doi=10.1111/jfb.14997|pmid=35137410|bibcode=2022JFBio.100..793G |s2cid=246678758|issn=1095-8649|url-access=subscription}}</ref>)
** ''[[Polydactylus approximans]]'' <small>([[George Tradescant Lay|Lay]] & [[Edward Turner Bennett|Bennett]], 1839)</small> (Blue bobo)
** ''[[Polydactylus luparensis]]'' <small>[[Pek Khiok Annie Lim|Lim]], Motomura & [[Albert Chuan Gambag|Gambang]], 2010</small> (Sarawak giant threadfin)
** ''[[Polydactylus macrochir]]'' <small>([[Albert Günther|Günther]], 1867)</small> ([[King threadfin]])
** ''[[Polydactylus macrophthalmus]]'' <small>([[Pieter Bleeker|Bleeker]], 1858)</small> (River threadfin)
** ''[[Polydactylus malagasyensis]]'' <small>Motomura & Iwatsuki, 2001</small> (African blackspot threadfin)
** ''[[Polydactylus microstomus]]'' <small>([[Pieter Bleeker|Bleeker]], 1851)</small> (Smallmouth threadfin)
** ''[[Polydactylus mullani]]'' <small>(Hora, 1926)</small> (Arabian blackspot threadfin)
** ''[[Polydactylus multiradiatus]]'' <small>([[Albert Günther|Günther]], 1860)</small> (Australian threadfin)
** ''[[Polydactylus nigripinnis]]'' <small>[[Ian Stafford Ross Munro|Munro]], 1964</small> (Blackfin threadfin)
** ''[[Polydactylus octonemus]]'' <small>([[Charles Frédéric Girard|Girard]], 1858)</small> (Atlantic threadfin)
** ''[[Polydactylus oligodon]]'' <small>([[Albert Günther|Günther]], 1860)</small> (Littlescale threadfin)
** ''[[Polydactylus opercularis]]'' <small>[[Alvin Seale|Seale]] & [[Barton Appler Bean|Bean]], 1907</small> (Yellow bobo)
** ''[[Polydactylus persicus]]'' <small>Motomura & Iwatsuki, 2001</small> (Persian blackspot threadfin)
** ''[[Polydactylus quadrifilis]]'' <small>([[Georges Cuvier|Cuvier]], 1829)</small> (Giant African threadfin)
** ''[[Polydactylus sextarius]]'' <small>([[Marcus Elieser Bloch|Bloch]] & [[Johann Gottlob Schneider|Schneider]], 1801)</small> (Blackspot threadfin)
** ''[[Polydactylus virginicus]]'' <small>([[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]])</small> (Barbu)
* Genus ''[[Polynemus]]''
** ''[[Polynemus aquilonaris]]'' <small>Motomura, 2003</small> ([[Northern paradise fish]])
** ''[[Polynemus bidentatus]]'' <small>Motomura & Tsukawaki, 2006</small>
** ''[[Polynemus dubius]]'' <small>[[Pieter Bleeker|Bleeker]], 1854</small> ([[Eastern paradise fish]])
** ''[[Polynemus hornadayi]]'' <small>[[George S. Myers|Myers]], 1936</small> ([[Hornaday's paradise fish]])
** ''[[Polynemus kapuasensis]]'' <small>Motomura & [[Martien JP van Oijen|van Oijen]], 2003</small> ([[Kapuas elegant paradise fish]])
** ''[[Polynemus melanochir]]'' <small>[[Achille Valenciennes|Valenciennes]], 1831</small> ([[Blackhand paradise fish]])
** ''[[Polynemus multifilis]]'' <small>[[Coenraad Jacob Temminck|Temminck]] & [[Hermann Schlegel|Schlegel]], 1843</small> ([[Elegant paradise fish]])
** ''[[Polynemus paradiseus]]'' <small>[[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]</small> ([[Paradise threadfin]])

==Timeline of genera==

<timeline>
ImageSize  = width:1000px height:auto barincrement:15px
PlotArea   = left:10px bottom:50px top:10px right:10px

Period      = from:-65.5 till:10
TimeAxis    = orientation:horizontal
ScaleMajor  = unit:year increment:5 start:-65.5
ScaleMinor  = unit:year increment:1 start:-65.5
TimeAxis    = orientation:hor
AlignBars   = justify

Colors =
 #legends
  id:CAR	  value:claret
  id:ANK 	 value:rgb(0.4,0.3,0.196)
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  id:OMN	  value:blue
  id:black        value:black
  id:white        value:white
  id:cenozoic     value:rgb(0.54,0.54,0.258)
  id:paleogene     value:rgb(0.99,0.6,0.32) 
  id:paleocene     value:rgb(0.99,0.65,0.37) 
  id:eocene     value:rgb(0.99,0.71,0.42) 
  id:oligocene     value:rgb(0.99,0.75,0.48) 
  id:neogene     value:rgb(0.999999,0.9,0.1) 
  id:miocene     value:rgb(0.999999,0.999999,0) 
  id:pliocene     value:rgb(0.97,0.98,0.68)  
  id:quaternary   value:rgb(0.98,0.98,0.5)
  id:pleistocene   value:rgb(0.999999,0.95,0.68)
  id:holocene   value:rgb(0.999,0.95,0.88)
 
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 bar:periodtop
 from: -65.5   till:  -55.8    color:paleocene  text:[[Paleocene]]
 from: -55.8   till:  -33.9    color:eocene  text:[[Eocene]] 
 from: -33.9   till:  -23.03    color:oligocene  text:[[Oligocene]]            
 from: -23.03    till: -5.332    color:miocene    text:[[Miocene]]
 from: -5.332    till: -2.588    color:pliocene    text:[[Plio.]]
 from: -2.588    till: -0.0117   color:pleistocene    text:[[Pleist.]]
 from: -0.0117    till: 0    color:holocene    text:[[Holocene|H.]]

 bar:eratop
 from: -65.5   till:  -23.03    color:paleogene  text:[[Paleogene]]         
 from: -23.03    till: -2.588    color:neogene    text:[[Neogene]]
 from: -2.588    till: 0   color:quaternary    text:[[Quaternary|Q.]]

PlotData=
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 color:miocene bar:NAM1  from:	-23.03	till:	0	text:	[[Pentanemus]]
 color:miocene bar:NAM2  from:	-11.608	till:	0	text:	[[Polydactylus]]

PlotData=
 align:center textcolor:black fontsize:M mark:(line,black) width:25

 bar:period
 from: -65.5   till:  -55.8    color:paleocene  text:[[Paleocene]]
 from: -55.8   till:  -33.9    color:eocene  text:[[Eocene]] 
 from: -33.9   till:  -23.03    color:oligocene  text:[[Oligocene]]            
 from: -23.03    till: -5.332    color:miocene    text:[[Miocene]]
 from: -5.332    till: -2.588    color:pliocene    text:[[Plio.]]
 from: -2.588    till: -0.0117   color:pleistocene    text:[[Pleist.]]
 from: -0.0117    till: 0    color:holocene    text:[[Holocene|H.]]

 bar:era
 from: -65.5   till:  -23.03    color:paleogene  text:[[Paleogene]]         
 from: -23.03    till: -2.588    color:neogene    text:[[Neogene]]
 from: -2.588    till: 0   color:quaternary    text:[[Quaternary|Q.]]

</timeline>

==References==
{{Reflist|30em|refs=
<ref name=krisnawati&umemoto>{{cite journal|last1=Suryanata |first1=Krisnawati  |author-link1=<!--Krisnawati Suryanata-->|last2=Umemoto |first2=Karen N. |author-link2=<!--Karen N. Umemoto--> |title=Tension at the nexus of the global and local: culture, property, and marine aquaculture in Hawaiʻi |journal=Environment and Planning A |volume=35 |issue=2 |year=2005 |pages=199, 206<!--199–213--> |doi=10.1068/a35116|citeseerx=10.1.1.456.680 |s2cid=143928957 }}</ref>
}}
{{more footnotes|date=November 2008}}
* {{FishBase family | family = Polynemidae | month = January | year = 2006}}
* {{cite journal|last=Sepkoski |first=Jack |title=A compendium of fossil marine animal genera |journal=Bulletins of American Paleontology |volume=364 |page=560 |year=2002 |url=http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class |access-date=2011-05-19 |archive-url=https://web.archive.org/web/20090220223520/http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class |archive-date=2009-02-20 }}

==External links==
*[http://www.fish.wa.gov.au/About-Us/Publications/Recreational-Fishing/Pages/Fact-Sheets.aspx Fisheries Western Australia - Threadfins Fact Sheet]
*[https://web.archive.org/web/20040217232857/http://www.practicalfishkeeping.co.uk/pfk/pages/show_article.php?article_id=111 The Paradise threadfin, Polynemus paradiseus]
*[https://web.archive.org/web/20040223170521/http://www.oar.noaa.gov/spotlite/archive/spot_hawaii.html Offshore aquaculture project yields a traditional Hawaiian delicacy]

{{Taxonbar|from=Q924957}}

[[Category:Polynemidae| ]]
[[Category:Fish of Hawaii]]
[[Category:Taxa named by Constantine Samuel Rafinesque]]

[[id:Senangin]]