# Threadfin jack

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Species of fish

Threadfin jack Conservation status Least Concern (IUCN 3.1)[1] Scientific classification Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Carangiformes Suborder: Carangoidei Family: Carangidae Genus: Euprepocaranx Kimura, Takeuchi & Yadome, 2022 Species: E. dorsalis Binomial name Euprepocaranx dorsalis (Gill, 1863) Approximate range of the threadfin jack Synonyms[2] Caranx otrynter Jordan & Gilbert, 1883 Carangoides dorsalis Gill, 1863 Carangoides otrynter (Jordan & Gilbert, 1883) Caranx dorsalis (Gill, 1863) Citula dorsalis (Gill, 1863) Paraselene otrynter (Jordan & Gilbert, 1883)

The **threadfin jack** or **thread pompano**, ***Euprepocaranx dorsalis***, is a species of coastal [marine](/source/Marine_(ocean)) [fish](/source/Fish) in the jack [family](/source/Family_(taxonomy)) [Carangidae](/source/Carangidae). The species inhabits the tropical waters of the eastern [Pacific Ocean](/source/Pacific_Ocean) from [Baja California](/source/Baja_California) in the north to [Ecuador](/source/Ecuador) and the [Galapagos Islands](/source/Galapagos_Islands) in the south. It is a moderately large fish, growing to 60 cm (24 in) and may be recognized by its filamentous [dorsal](/source/Dorsal_fin) and [anal fin](/source/Anal_fin) lobes. The threadfin jack inhabits both deeper [coastal](/source/Coastal) waters and [inshore](/source/Inshore) environments, including [reefs](/source/Reef) and [estuaries](/source/Estuaries), where it preys on minute [benthic](/source/Benthic) and [pelagic](/source/Pelagic) organisms, including small fishes and [crustaceans](/source/Crustacean). Very little is known about the ecology and reproductive cycle in the species. The threadfin jack is of importance to [fisheries](/source/Fisheries) throughout its distribution, caught by [hook-and-line](/source/Fishing_hook) and [net](/source/Fishing_net) methods and marketed fresh and salted, and is considered a very good [table fish](/source/Fish_(food)). The species was named *Carangoides dorsalis* by [Theodore Gill](/source/Theodore_Gill) 20 years before the name *Caranx otrynter* was introduced, but confusion with *Vomer dorsalis* led to the proposal of the new name to separate the two species.

## Taxonomy and naming

The threadfin jack is currently placed within the [monotypic genus](/source/Monotypic_taxon) *Euprepocaranx*.[3] The threadfin jack is a member of the jack and horse mackerel family [Carangidae](/source/Carangidae), which are, in turn, within the [order](/source/Order_(biology)) [Carangiformes](/source/Carangiformes).[4]

The species was first [scientifically described](/source/Scientific_classification) by the American [ichthyologist](/source/Ichthyologist) [Theodore Gill](/source/Theodore_Gill), who named the species *Carangoides dorsalis* based on the [holotype](/source/Holotype) taken from the west coast of [Central America](/source/Central_America).[5] This name and description was published in the *Proceedings of the Academy of Natural Sciences* of Philadelphia, in which Gill one year previously described another carangid, *Vomer dorsalis*.[6] The state of carangid [taxonomy](/source/Taxonomy_(biology)) at the time was rather confusing, with many synonymous genera and species present in the literature, and *Vomer dorsalis* was soon moved to *Caranx*, as was *Carangoides dorsalis*, creating a taxonomic [homonym](/source/Homonym). To address this problem, the American ichthyologists [David Starr Jordan](/source/David_Starr_Jordan) and [Charles Henry Gilbert](/source/Charles_Henry_Gilbert) in 1883 created the name *Caranx otrynter* as a replacement for the species originally named *Carangoides dorsalis*, basing their description on a new holotype specimen taken from [Mazatlán](/source/Mazatl%C3%A1n), Mexico.[7] The authors indicated that if *Vomer* was found to be a valid genus or subgenus, *Vomer dorsalis* could be reinstated and the original combination of *Caranx dorsalis* be restored. Despite *V. dorsalis* being transferred to *[Selene dorsalis](https://en.wikipedia.org/w/index.php?title=Selene_dorsalis&action=edit&redlink=1)*, this never occurred and in a 1994 publication, Gerald Allen and D. Ross Robertson placed *Caranx otrynter* into the genus *Carangoides*,[8] where it has remained until 2022.[9] The specific name *otrynter* is derived from Latin, and means a driver, in allusion to the [whip](/source/Whip)-like ray of the second dorsal fin.[7] The common names of the species, threadfin jack and thread pompano, also refer to the filamentous, threadlike dorsal fin.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

## Description

The threadlike dorsal and anal fin tips are characteristic.

The threadfin jack is a moderately large species, growing to a known maximum length of 60 cm.[10] The species is similar in appearance to a number of jacks in the genera *Carangoides* and *[Alectis](/source/Alectis)* in its adult form, having a compressed, [oblong](/source/Rectangle) body, with the [dorsal](/source/Anatomical_terms_of_location#Dorsal_and_ventral) and ventral profiles approximately equal in [concavity](https://en.wiktionary.org/wiki/concave). The head profile is quite angular, being most steep immediately above the mouth, and being moderately steep to the [nape](/source/Nape), becoming more horizontal [posteriorly](/source/Anatomical_terms_of_location#Anterior_and_posterior). The juveniles have a more oval to diamond shape, looking much like juveniles of the genus *Alectis*.[11] The [dorsal fin](/source/Dorsal_fin) is in two parts, the first being greatly diminished and consisting of eight [spines](/source/Fish_anatomy#Spines_and_rays) entirely embedded in the skin, with the second dorsal fin composed of one spine and 18 or 19 [soft rays](/source/Fish_anatomy#Spines_and_rays). The [anal fin](/source/Anal_fin) is composed of two [anteriorly](/source/Anatomical_terms_of_location#Anterior_and_posterior) detached spines followed by one spine and 16 or 17 soft rays.[11] Both juveniles and adults have highly elongated second dorsal and anal fin lobes, extended out into long filaments; they are most pronounced in juveniles.[12] The [lateral line](/source/Lateral_line) has a moderate, regular arch anteriorly, which is roughly equal in length to the straight posterior section. The straight section has no to 15 [scales](/source/Scale_(zoology)) followed by 40 to 52 small [scutes](/source/Scute). The breast is devoid of scales ventrally to behind the [pelvic fin](/source/Pelvic_fin) origin and diagonally up to the [pectoral fin](/source/Pectoral_fin) base. Both [jaws](/source/Jaw) contain uniform bands of small, weak teeth becoming wider posteriorly and irregular conical outer teeth in adults. It has 21 to 23 [gill rakers](/source/Gill_raker) and 24 [vertebrae](/source/Vertebrae).[11]

In life, the threadfin jack is a silvery-blue above, becoming silvery-white on the underside, with golden to yellow reflections. The first dorsal and pelvic fin is grey, while the second dorsal, anal, pectoral, and [caudal fins](/source/Caudal_fin) are [hyaline](/source/Hyaline) or grey with a yellow tinge. Juveniles have clear, dark, vertical bands, fading with age. Much like the [shadow trevally](/source/Shadow_trevally), small black spots occur on the bases of soft dorsal rays and the body immediately below them that increase in size with age, with a small black blotch on the upper [operculum](/source/Operculum_(fish)).[11]

## Distribution and habitat

The threadfin jack is distributed throughout the [tropical](/source/Tropical) regions of the eastern [Pacific Ocean](/source/Pacific_Ocean), inhabiting the western coast of the [Americas](/source/Americas). The northern limit to the species range is southern [Baja California](/source/Baja_California), with its range extending south to [Mexico](/source/Mexico) and [Central America](/source/Central_America) to a southern limit of [Ecuador](/source/Ecuador), with the species also recorded from the [Galapagos Islands](/source/Galapagos_Islands).[10] It is one of only two species of the genus *Carangoides* found on the western coastline of the Americas, with the other species being the widely distributed [island trevally](/source/Island_trevally), *Carangoides orthogrammus*.[11]

The species appears to undergo a major transition in lifestyle after its juvenile phase, with young individuals leading a [pelagic](/source/Pelagic) lifestyle, able to be transported to [offshore](/source/Shore) islands such as the Galapagos by currents. Older individuals are more [benthic](/source/Benthic) in nature, inhabiting the bottom of the water column in mostly [coastal](/source/Coastal) waters on [reefs](/source/Reef).[13] Smaller fish have been recorded from [estuaries](/source/Estuaries), [mangrove](/source/Mangrove)-lined creeks, shallow [bays](/source/Bay), and [lagoons](/source/Lagoon),[14] although larger fish live in much deeper waters up to 50 m (160 ft) in depth.[15]

## Biology and fishery

Much of biology and ecology of the threadfin jack is unknown, with the species' diet the only studied aspect of its biology. A study in fishes of the continental shelf of [Colombia](/source/Colombia) found the species takes predominantly small, benthic fishes of the families [Triglidae](/source/Triglidae), [Synodontidae](/source/Synodontidae), and [Batrachoididae](/source/Batrachoididae). Other common prey included benthic [crustaceans](/source/Crustaceans), including various [crabs](/source/Crab) and [shrimp](/source/Shrimp).[16] Nothing is known of its reproductive cycle.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

The threadfin jack is of some importance to [fisheries](/source/Fisheries) throughout its range, although individual catch statistics for the species are not kept. It is often caught by hook-and-line methods or by [gill nets](/source/Gill_net) and various artisanal traps. It is considered to be good to excellent [table fare](/source/Fish_(food)), and is marketed both fresh and [salted](/source/Salting_(food)).[11] The species has also been found at a number of [archaeological](/source/Archaeological) sites in both [Panama](/source/Panama) and Ecuador, indicating it has been caught by humans for food for at least 3450 years.[14][17] The threadfin jack is also of interest to [anglers](/source/Angling) who catch the species occasionally, and is considered a minor [gamefish](/source/Gamefish). Juveniles are occasionally caught from shore, such as [piers](/source/Pier) and [breakwaters](/source/Breakwater_(structure)), while larger individuals are caught over deeper reefs. The species takes a variety of [bait](/source/Bait_(fishing)), including fish and prawns, but they also take [lures](/source/Fishing_lure), including hard and small, fly-like Sabiki lures.[15]

## References

1. **[^](#cite_ref-iucn_status_19_November_2021_1-0)** Smith-Vaniz, B.; Robertson, R.; Dominici-Arosemena, A.; Bussing, W.; Molina, H. (2010). ["*Carangoides otrynter*"](https://www.iucnredlist.org/species/183808/8180545). *[IUCN Red List of Threatened Species](/source/IUCN_Red_List)*. **2010** e.T183808A8180545. [doi](/source/Doi_(identifier)):[10.2305/IUCN.UK.2010-3.RLTS.T183808A8180545.en](https://doi.org/10.2305%2FIUCN.UK.2010-3.RLTS.T183808A8180545.en). Retrieved 19 November 2021.

1. **[^](#cite_ref-2)** Fricke, Ron; [Eschmeyer, William N.](/source/William_N._Eschmeyer) & van der Laan, Richard (eds.). ["Species related to *Euprepocaranx dorsalis*"](http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatget.asp?tbl=species&genus=Euprepocaranx&species=dorsalis). *[Catalog of Fishes](/source/Catalog_of_Fishes)*. [California Academy of Sciences](/source/California_Academy_of_Sciences). Retrieved 5 March 2026.

1. **[^](#cite_ref-KTY_3-0)** Kimura, Seishi, Shun Takeuchi, and Taishi Yadome. "Generic revision of the species formerly belonging to the genus Carangoides and its related genera (Carangiformes: Carangidae)." Ichthyological Research 69.4 (2022): 433-487.

1. **[^](#cite_ref-Nelson5_4-0)** Nelson, Joseph S.; Grande, Terry C.; Wilson, Mark V. H. (2016). [*Fishes of the World*](https://books.google.co.uk/books?id=E-MLDAAAQBAJ&pg=PP1) (5th ed.). Hoboken: John Wiley and Sons. pp. 380–387. [doi](/source/Doi_(identifier)):[10.1002/9781119174844](https://doi.org/10.1002%2F9781119174844). [ISBN](/source/ISBN_(identifier)) [978-1-118-34233-6](https://en.wikipedia.org/wiki/Special:BookSources/978-1-118-34233-6).

1. **[^](#cite_ref-5)** Gill, Theodore N. (1863). "Descriptive enumeration of a collection of fishes from the western coast of Central America, presented to the Smithsonian Institution by Captain John M. Dow". *Proceedings of the Academy of Natural Sciences of Philadelphia*. **15**: 162–174.

1. **[^](#cite_ref-6)** Gill, Theodore N. (1862). "Synopsis of the carangoids of the eastern coast of North America". *Proceedings of the Academy of Natural Sciences of Philadelphia*. **14** (9): 430–443.

1. ^ [***a***](#cite_ref-proc_7-0) [***b***](#cite_ref-proc_7-1) Jordan, David S.; Charles H. Gilbert (1883). "A Review of the American Caranginae". *Proceedings of the United States National Museum*. **6** (367): 188–207. [doi](/source/Doi_(identifier)):[10.5479/si.00963801.6-367.188](https://doi.org/10.5479%2Fsi.00963801.6-367.188).

1. **[^](#cite_ref-8)** Allen, Gerald A.; D.R. Robertson (1994). *Fishes of the tropical eastern Pacific i-xix*. Bathurst: Crawford House Press. pp. 1–332. [ISBN](/source/ISBN_(identifier)) [978-0-8248-1675-9](https://en.wikipedia.org/wiki/Special:BookSources/978-0-8248-1675-9).

1. **[^](#cite_ref-9)** Kimura, S.; Takeuchi, S.; Yadome, T. (2022). "Generic revision of the species formerly belonging to the genus *Carangoides* and its related genera (Carangiformes: Carangidae)". *Ichthyological Research*. **69** (4): 433–487. [doi](/source/Doi_(identifier)):[10.1007/s10228-021-00850-1](https://doi.org/10.1007%2Fs10228-021-00850-1).

1. ^ [***a***](#cite_ref-fishbase_10-0) [***b***](#cite_ref-fishbase_10-1) [Froese, Rainer](/source/Rainer_Froese); [Pauly, Daniel](/source/Daniel_Pauly) (eds.). ["*Euprepocaranx dorsalis*"](https://www.fishbase.org/summary/SpeciesSummary.php?genusname=Euprepocaranx&speciesname=dorsalis). *[FishBase](/source/FishBase)*. March 2026 version.

1. ^ [***a***](#cite_ref-FAOPCO_11-0) [***b***](#cite_ref-FAOPCO_11-1) [***c***](#cite_ref-FAOPCO_11-2) [***d***](#cite_ref-FAOPCO_11-3) [***e***](#cite_ref-FAOPCO_11-4) [***f***](#cite_ref-FAOPCO_11-5) Fischer, W.; Krupp F.; Schneider W.; Sommer C.; Carpenter K.E.; Niem V.H. (1995). [*Guía FAO para la identificación de especies para los fines de la pesca. Pacífico centro-oriental. Volumen II. Vertebrados - Parte 1*](http://www.fao.org/fishery/sidp/3,1/en#Ecp). Rome: FAO. p. 958. [ISBN](/source/ISBN_(identifier)) [92-5-303409-2](https://en.wikipedia.org/wiki/Special:BookSources/92-5-303409-2).

1. **[^](#cite_ref-12)** Grove, Jack S.; Robert J. Lavenberg (1997). *The Fishes of the Galápagos Islands*. California: Stanford University Press. p. 376. [ISBN](/source/ISBN_(identifier)) [978-0-8047-2289-6](https://en.wikipedia.org/wiki/Special:BookSources/978-0-8047-2289-6).

1. **[^](#cite_ref-13)** Dominici-Arosemena, Arturo; Matthias Wolff (2006). ["Reef fish community structure in the Tropical Eastern Pacific (Panama): living on a relatively stable rocky reef environment"](https://doi.org/10.1007%2Fs10152-006-0045-4). *Helgoland Marine Research*. **60** (4): 287–305. [Bibcode](/source/Bibcode_(identifier)):[2006HMR....60..287D](https://ui.adsabs.harvard.edu/abs/2006HMR....60..287D). [doi](/source/Doi_(identifier)):[10.1007/s10152-006-0045-4](https://doi.org/10.1007%2Fs10152-006-0045-4).

1. ^ [***a***](#cite_ref-ns_14-0) [***b***](#cite_ref-ns_14-1) Cooke, Richard (1992). "Prehistoric Nearshore and Littoral Fishing in the Eastern Tropical Pacific: An Ichthyological Evaluation". *Journal of World Prehistory*. **6** (1): 1–49. [doi](/source/Doi_(identifier)):[10.1007/BF00997584](https://doi.org/10.1007%2FBF00997584). [S2CID](/source/S2CID_(identifier)) [161134586](https://api.semanticscholar.org/CorpusID:161134586).

1. ^ [***a***](#cite_ref-Mexfish_15-0) [***b***](#cite_ref-Mexfish_15-1) ["Threadfin Jack, Thread Pompano"](http://www.mexfish.com/fish/thrjck/thrjck.htm). *Fish Identification*. Mexfish.com. 2007. Retrieved 2007-09-27.

1. **[^](#cite_ref-16)** López-Peraltaand, R.H.; C.A.T. Arcila (2002). ["Diet Composition of Fish Species from the Southern Continental Shelf of Colombia"](http://www.worldfishcenter.org/naga/Naga25-3&4/pdf/NAGA_25no3n4_features_e.pdf) (PDF). *Naga, WorldFish Center Quarterly*. **25** (3–4): 23–29. Retrieved 2007-09-27.

1. **[^](#cite_ref-17)** Stahl, Peter W. (2003). "The Zooarchaeological Record from Formative Ecuador". In Raymond, J.S. & Burger R.L. (ed.). *Archaeology of Formative Ecuador*. Washington D.C: Dumbarton Oaks Research Library and Collection. p. 198. [ISBN](/source/ISBN_(identifier)) [978-0-88402-292-3](https://en.wikipedia.org/wiki/Special:BookSources/978-0-88402-292-3).

## External links

- [Mexfish fact sheet and photographs](http://www.mexfish.com/fish/thrjck/thrjck.htm)

Taxon identifiers Carangoides otrynter Wikidata: Q2220629 Wikispecies: Carangoides otrynter BOLD: 601384 CoL: R2JP FishBase: 1915 GBIF: 5210568 iNaturalist: 96737 IRMNG: 10759017 ITIS: 641957 IUCN: 183808 NCBI: 179362 OBIS: 276243 Open Tree of Life: 637329 WoRMS: 276243 Caranx otrynter Wikidata: Q106413317 CoL: R2S3 GBIF: 2390995 IRMNG: 10154254 ITIS: 641959 WoRMS: 302411

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