# Shadow trevally

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Species of ray-finned fish

Shadow trevally Conservation status Least Concern (IUCN 3.1)[1] Scientific classification Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Carangiformes Suborder: Carangoidei Family: Carangidae Genus: Carangichthys Species: C. dinema Binomial name Carangichthys dinema (Bleeker, 1851) Approximate range of the shadow trevally Synonyms[2] Carangoides dinema Bleeker, 1851 Caranx dinema (Bleeker, 1851) Carangichthys typus Bleeker, 1853 Caranx longipes Steindachner, 1906

The **shadow trevally** (***Carangichthys dinema***), also known as the **shadow kingfish**, **twothread trevally** or **Aldabra trevally**, is a [species](/source/Species) of inshore [marine](/source/Marine_(ocean)) [fish](/source/Fish) in the jack [family](/source/Family_(taxonomy)) [Carangidae](/source/Carangidae). The species is patchily distributed throughout the [tropical](/source/Tropical) and subtropical waters of the [Indian](/source/Indian_Ocean) and west [Pacific Oceans](/source/Pacific_Ocean), from [South Africa](/source/South_Africa) in the west to [Japan](/source/Japan) and [Samoa](/source/Samoa) in the east, reaching as far south as [Indonesia](/source/Indonesia) and [New Caledonia](/source/New_Caledonia). It is most easily distinguished from similar species by as series of dark rectangular blotches under the second [dorsal fin](/source/Dorsal_fin), giving a 'shadowed' appearance, from which its [common name](/source/Common_name) is derived. The shadow trevally is a reasonably large fish, growing to 85 cm in length and at least 2.6 kg in weight. It inhabits shallow [coastal](/source/Coastal) waters, including [reefs](/source/Reef), [bays](/source/Bay), and [estuaries](/source/Estuaries), where it takes small fish and benthic [crustaceans](/source/Crustacean) as prey. Nothing is known of the species' [ecology](/source/Ecology) and [reproductive biology](/source/Reproductive_biology). It is of little importance to [fisheries](/source/Fisheries), and is occasionally taken by bottom [trawls](/source/Fishing_trawler) and other [artisanal fishing](/source/Artisanal_fishing) gear.

## Taxonomy and naming

The shadow trevally is presently classified within the [genus](/source/Genus) *[Carangichthys](/source/Carangichthys)*, one of a number of genera referred to as trevallies.[2] *Carangichthys* is further classified in the family [Carangidae](/source/Carangidae), and Carangidae is part of the [order](/source/Order_(biology)) [Carangiformes](/source/Carangiformes).[3]

The species was first [scientifically described](/source/Scientific_classification) and named by the Dutch [ichthyologist](/source/Ichthyologist) [Pieter Bleeker](/source/Pieter_Bleeker) in 1851 based on a specimen collected from the waters off [Jakarta](/source/Jakarta), located on [Java](/source/Java) in [Indonesia](/source/Indonesia), which was designated to be the [holotype](/source/Holotype).[4] He named this new species *[Carangoides](/source/Carangoides) dinema*, with the specific name derived from the Latin *dis*, meaning two and the Greek *nema*, meaning thread, referring to the fin anatomy of the species. The species is quite unique in the comparatively simple [taxonomic history](/source/Taxonomy_(biology)) it has, with other related species often renamed and transferred between genera many times. The species is most [commonly termed](/source/Common_name) the 'shadow trevally' or 'shadow kingfish' in reference to a series of small dark blotches positioned on the upper side, underneath the second dorsal fin, giving the appearance of shadow from the fin itself. Other names used for the species include 'two-thread trevally' and 'Aldabra trevally'.[5]

## Description

An angler's catch of shadow trevally

The shadow trevally is similar in form to a number of other jacks in the family Carangidae, having an almost [ovate](/source/Glossary_of_ichthyology#O), strongly compressed body.[6] It is fairly large fish, growing to a maximum known length of 85 cm[7] and a recorded weight of 2.6 [kg](/source/Kilogram).[5] The [dorsal](/source/Anatomical_terms_of_location#Dorsal_and_ventral) profile is strongly convex, while the [ventral](/source/Anatomical_terms_of_location#Dorsal_and_ventral) profile is less so, even tending to be concave between the snout and the [anal fin](/source/Anal_fin), while the [nape](/source/Nape) is elevated and almost straight in profile.[6] There are two separate [dorsal fins](/source/Dorsal_fin), the first consisting of 8 [spines](/source/Fish_anatomy#Spines_and_rays) and second of a single spine and 17 to 19 [soft rays](/source/Fish_anatomy#Spines_and_rays). The lobe of the second dorsal fin is elongated, being greater than the head length. The anal fin is composed of two [anteriorly](/source/Anatomical_terms_of_location#Anterior_and_posterior) detached spines followed by a single spine and 15 to 17 soft rays.[8] The [lateral line](/source/Lateral_line) has a moderate arch anteriorly, with the junction of the curved and straight sections below the tenth or twelfth soft rays of the second dorsal fin. The curved section of the lateral line is slightly longer than the straight section, and contains 60 to 63 [scales](/source/Scale_(zoology)), while the straight part contains no to six scales followed by 23 to 30 [scutes](/source/Scutes). The breast is devoid of scales ventrally to behind the [pelvic fin](/source/Pelvic_fin) origin and up to the [pectoral fin](/source/Pectoral_fin) base, although in rare cases this is interrupted by a lateral band of scales.[8] Both [jaws](/source/Jaw) contain bands of small teeth, with the bands becoming wider anteriorly, and the upper jaw also has an irregular outer series of moderately large teeth, with large specimens also showing this in the lower jaw. It has a total of 24 to 28 [gill rakers](/source/Gill_raker) and 24 [vertebrae](/source/Vertebrae).[6]

In life, the shadow trevally is a bluish-green colour above, fading to a silvery white on the underside. It takes its common name from a series of small black-brown rectangular blotches which become larger posteriorly on its back between the bases of the second dorsal fin rays. Also, a dark-brown, diffuse blotch is present on the [operculum](/source/Operculum_(fish)). The spinous dorsal fin is pale to dusky, while the second dorsal fin lobe is dusky with the ray tips yellowish. The anal fin distal margin is whitish-blue, and the [caudal fin](/source/Caudal_fin) has a yellowish upper lobe and pale trailing edges and lower lobe tip. The pectoral fins are [hyaline](/source/Hyaline) and the pelvic fins are whitish to dusky.[6]

## Distribution and habitat

The shadow trevally is distributed patchily throughout the [tropical](/source/Tropical) to subtropical waters of the [Indian](/source/Indian_Ocean) and west [Pacific Oceans](/source/Pacific_Ocean). The species' westernmost limit is a section of the [east African](/source/East_Africa) coast from [South Africa](/source/South_Africa) to [Tanzania](/source/Tanzania). No records exist for the species further north until [India](/source/India) and [Sri Lanka](/source/Sri_Lanka).[9] In the Pacific, the species is known from [China](/source/China), [Korea](/source/Korea), [Southeast Asia](/source/Southeast_Asia), and the [Indonesian](/source/Indonesia) and [Philippines](/source/Philippines) island chains. Its easternmost limit extends to [Taiwan](/source/Taiwan) and [Japan](/source/Japan) in the north and a number of small island groups including [Tonga](/source/Tonga) and [Samoa](/source/Samoa) in the south.[5]

The shadow trevally inhabits [coastal](/source/Coastal) waters at depths generally less than 15 m. It is known to Kruise in small schools along the shallow edge of steep [reef](/source/Reef) drop-offs,[5] and has also been recorded from [bays](/source/Bay) and [estuaries](/source/Estuaries).[10] The species has been recorded around [shipwrecks](/source/Shipwreck), and one study showed it was one of the first fish to move in after a ship was scuttled.[11]

## Biology and fishery

The biology and [ecology](/source/Ecology) of the shadow trevally is poorly known. It is known to live either in small schools or individually, and is a [predatory](/source/Predator) fish, taking small fish and benthic [crustaceans](/source/Crustacean).[5] Nothing is known of its movements or [reproduction](/source/Reproduction).

The shadow trevally is of little importance to fisheries throughout its range, taken as [bycatch](/source/Bycatch) and generally not distinguished from other carangid species. It is often taken by bottom [trawls](/source/Trawl) and various kinds of [artisanal](/source/Artisanal) fishing gear.[6]

## References

1. **[^](#cite_ref-iucn_1-0)** Smith-Vaniz, W.F. & Williams, I. (2017) [errata version of 2016 assessment]. ["*Carangoides dinema*"](https://www.iucnredlist.org/species/20429438/115372384). *[IUCN Red List of Threatened Species](/source/IUCN_Red_List)*. **2016** e.T20429438A115372384. [doi](/source/Doi_(identifier)):[10.2305/IUCN.UK.2016-3.RLTS.T20429438A65927713.en](https://doi.org/10.2305%2FIUCN.UK.2016-3.RLTS.T20429438A65927713.en). Retrieved 12 November 2022.

1. ^ [***a***](#cite_ref-ECoF_species_2-0) [***b***](#cite_ref-ECoF_species_2-1) Fricke, Ron; [Eschmeyer, William N.](/source/William_N._Eschmeyer) & van der Laan, Richard, eds. (12 February 2026). ["Species in the genus *Carangichthys*"](http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatget.asp?tbl=species&genus=Carangichthys). *[Catalog of Fishes](/source/Catalog_of_Fishes)*. [California Academy of Sciences](/source/California_Academy_of_Sciences).

1. **[^](#cite_ref-Nelson5_3-0)** J. S. Nelson; T. C. Grande; M. V. H. Wilson (2016). [*Fishes of the World*](https://sites.google.com/site/fotw5th/) (5th ed.). Wiley. pp. 380–387. [ISBN](/source/ISBN_(identifier)) [978-1-118-34233-6](https://en.wikipedia.org/wiki/Special:BookSources/978-1-118-34233-6).

1. **[^](#cite_ref-Lin1999_4-0)** Lin, Pai-Lei; Shao, Kwang-Tsao (28 March 1999). ["A Review of the Carangid Fishes (Family Carangidae) From Taiwan with Descriptions of Four New Records"](http://cat.inist.fr/?aModele=afficheN&cpsidt=10055944). *Zoological Studies*. **38** (1): 33–68.

1. ^ [***a***](#cite_ref-fishbase_5-0) [***b***](#cite_ref-fishbase_5-1) [***c***](#cite_ref-fishbase_5-2) [***d***](#cite_ref-fishbase_5-3) [***e***](#cite_ref-fishbase_5-4) [Froese, Rainer](/source/Rainer_Froese); [Pauly, Daniel](/source/Daniel_Pauly) (eds.). ["*Carangoides dinema*"](https://www.fishbase.org/summary/SpeciesSummary.php?genusname=Carangoides&speciesname=dinema). *[FishBase](/source/FishBase)*. September 2008 version.

1. ^ [***a***](#cite_ref-FAO_6-0) [***b***](#cite_ref-FAO_6-1) [***c***](#cite_ref-FAO_6-2) [***d***](#cite_ref-FAO_6-3) [***e***](#cite_ref-FAO_6-4) Carpenter, Kent E.; Volker H. Niem, eds. (2001). [*FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volume 4: Bony fishes part 2 (Mugilidae to Carangidae)*](ftp://ftp.fao.org/docrep/fao/009/x2400e/x2400e52.pdf) (PDF). FAO. Rome: Food and Agriculture Organization of the United Nations. p. 2694. [ISBN](/source/ISBN_(identifier)) [92-5-104587-9](https://en.wikipedia.org/wiki/Special:BookSources/92-5-104587-9).

1. **[^](#cite_ref-7)** Kuiter, Rudie H.; T. Tonozuka (2001). *Pictorial guide to Indonesian reef fishes. Part 1. Eels- Snappers, Muraenidae - Lutjanidae*. Australia: Zoonetics. p. 302. [ISBN](/source/ISBN_(identifier)) [979-98188-1-8](https://en.wikipedia.org/wiki/Special:BookSources/979-98188-1-8).

1. ^ [***a***](#cite_ref-Tarp_8-0) [***b***](#cite_ref-Tarp_8-1) Gloerfelt-Tarp, Thomas; Patricia J. Kailola (1984). *Trawled Fishes of Southern Indonesia and Northeastern Australia*. Singapore: Australian Development Assistance Bureau. p. 285. [ISBN](/source/ISBN_(identifier)) [0-642-70001-X](https://en.wikipedia.org/wiki/Special:BookSources/0-642-70001-X).

1. **[^](#cite_ref-9)** Kapoor, D.; R. Dayal; A.G. Ponniah, eds. (2002). *Fish Biodiversity of India*. Lucknow: National Bureau of Fish Genetic Resources. p. 228. [ISBN](/source/ISBN_(identifier)) [81-901014-8-X](https://en.wikipedia.org/wiki/Special:BookSources/81-901014-8-X).

1. **[^](#cite_ref-10)** Kuo, S.R.; K.T. Shao (1999). ["Species composition of fish in the coastal zones of the Tsengwen estuary, with descriptions of five new records from Taiwan"](https://web.archive.org/web/20081204093753/http://zoolstud.sinica.edu.tw/Journals/38.4/391-404.pdf) (PDF). *Zoological Studies*. **38** (4): 391–404. Archived from [the original](http://zoolstud.sinica.edu.tw/Journals/38.4/391-404.pdf) (PDF) on 2008-12-04. Retrieved 2008-09-21.

1. **[^](#cite_ref-11)** Wantiez, Laurent; Pierre Thollotw (2000). "Colonisation of the F/V Caledonie Toho 2 Wreck by a Reef-Fish Assemblage Near Noumea (New Caledonia)". *Atoll Research Bulletin*. **485**: 2–19. [doi](/source/Doi_(identifier)):[10.5479/si.00775630.485.1](https://doi.org/10.5479%2Fsi.00775630.485.1).

## External links

- [Shadow trevally at Fishbase](http://www.fishbase.org/summary/SpeciesSummary.php?id=1925)

- [Encyclopedia of Life page](http://www.eol.org/taxa/17043863?category_id=1&expertise=expert)[*[permanent dead link](https://en.wikipedia.org/wiki/Wikipedia:Link_rot)*]

Taxon identifiers Carangoides dinema Wikidata: Q2562214 Wikispecies: Carangoides dinema AFD: Carangoides_dinema BOLD: 163290 CoL: R2HV FishBase: 1925 GBIF: 5210534 iNaturalist: 510462 IRMNG: 10722149 ITIS: 641978 IUCN: 20429438 NCBI: 1218181 OBIS: 218401 Open Tree of Life: 586580 Plazi: 19EA22DB-7C23-F75A-AEB0-A3BA9B4FF282 TaiCOL: t0030135 WoRMS: 218401 ZooBank: AE3CA683-60B8-425A-BF73-EA46AF59ABE0

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