Angler Flatfish, Asterorhombus cocosensis (Bleeker 1855)

Other Names: Angler Flounder, Cocos Island Flounder

An Angler Flatfish, Asterorhombus cocosensis, in Lembeh Strait, Sulawesi, Indonesia, 2014. Source: Jim Greenfield / FishBase. License: All rights reserved

A pale brown flounder finely mottled with numerous pale and dark spots, and widely spaced ocelli that are larger than the eye. The first dorsal-fin ray is elongate, separated from the remaining rays, and has a large leaf-like membrane or lure at the tip that is thought to resemble a shrimp or small fish. The blind side is uniformly pale.

Cite this page as:
Bray, D.J. 2021, Asterorhombus cocosensis in Fishes of Australia, accessed 21 Jun 2024,

Angler Flatfish, Asterorhombus cocosensis (Bleeker 1855)

More Info


Rowley Shoals, Western Australia, Beagle Gulf, Northern Territory, and the northern Great Barrier Reef, Queensland; also at Cocos (Keeling) Islands in the eastern Indian Ocean (the type locality). Elsewhere the species is widespread in the Indo-west-Pacific from East Africa to Fiji, north to the Ryukyu Islands and south to the Great Barrier Reef and New Caledonia.
Inhabits coral rubble, reef flats, and pale sandy areas near reefs, and coastal bays.


Dorsal fin 79-83; Anal fin 59-64; Pectoral fin 10-13 (eyed side), 8-11 (blind side); Caudal fin 2+13+2=17; lateral-line scales 52-58; Gill rakers 0 + 8-9; Vertebrae 10 + 25-26 = 35-36. 
Body depth 51.5-58.3; sexual dimorphism in interorbital width, in specimens approximately 6.0 cm SL, males 4.1-7.9, females 3.2-5.0.
First dorsal-fin ray with distinct membranous structure confined to tip, resembling a small fish or crustacean (possibly a small hippolytid shrimp).


The modified first dorsal-fin ray is tipped with a fleshy lure that resembles a small crustacean. The lure is waved back and forth near the mouth of the fish to attract prey. 


The species is named for the type locality, Cocos (Keeling) Islands in the eastern Indian Ocean.

Species Citation

Rhombus cocosensis Bleeker 1855, Natuurk. Tijdschr. Nederland. Indië 8: 179. Type locality: Cocos-Keeling Islands, Indian Ocean.


Bray, D.J. 2021


Atlas of Living Australia

Angler Flatfish, Asterorhombus cocosensis (Bleeker 1855)


Allen, G.R. & Erdmann, M.V. 2012. Reef fishes of the East Indies. Perth : Tropical Reef Research 3 vols, 1260 pp. (as Asterorhombus fijiensis)

Amaoka, K. & Arai, M. 1998. Redescription of a rare bothid, Asterorhombus bleekeri (Macleay), and description of a new species of Asterorhombus from northwestern Australia (Teleostei: Pleuronectiformes). Ichthyological Research 45(3): 249-257 (as Asterorhombus fijiensis).

Amaoka, K. & Ho, H-C. 2019. The lefteye flounder family Bothidae (Order Pleuronectiformes) of Taiwan. Zootaxa 4702(1): 155-215,

Amaoka, K., Senou, H. & Ono, A. 1994. Record of the bothid flounder Asterorhombus fijiensis from the western Pacific, with observations on the use of the first dorsal-fin ray as a lure. Japanese Journal of Ichthyology 41(1): 23-28 figs 1-3 (as Asterorhombus fijiensis).

Bleeker, P. 1855. Derde bijdrage tot de kennis der ichthyologische fauna van de Kokos-eilanden. Natuurkundig Tijdschrift voor Nederlandsch Indië 8: 169-180.

Hensley, D.A. 2003. On the status of Rhombus cocosensis Bleeker, and description of a new species of Engyprosopon based on misidentification of this species (Pleuronectiformes: Bothidae). Copeia 2003(4): 833-837.

Hensley, D.A. 2005. Revision of the genus Asterorhombus (Pleuronectiformes: Bothidae. Copeia 2005(3): 445-460.

Hensley, D.A. & Amaoka, K. 2001. Bothidae. pp. 3799-3841 in Carpenter, K.E. & Niem, T.H. (eds). The Living Marine Resources of the Western Central Pacific. FAO Species Identification Guide for Fisheries Purposes. Rome : FAO Vol. 6 pp. 3381-4218 (as Engyprosopon cocosensis)

Kuiter R.H. & Tonozuka, T. 2001. Indonesian Reef Fishes. Part 3. Jawfishes- Sunfishes, Opistognathidae- Molidae. Melbourne : Zoonetics pp. 623–893.

Munroe, T. 2016. Asterorhombus cocosensis. The IUCN Red List of Threatened Species 2016: e.T69741856A69742784. Downloaded on 10 February 2018.

Norman, J.R. 1931. Notes on flatfishes (Heterosomata). I. Notes on flatfishes of the family Bothidae in the British Museum, with descriptions of three new species. Annals and Magazine of Natural History 10 8(47): 507-510 (p. 508, described as Engyprosopon fijiensis)

Quick Facts

CAAB Code:37460057

Conservation:IUCN Least Concern

Depth:0-30 m

Habitat:Reef associated, sandy areas

Max Size:15 cm TL

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Species Maps

CAAB distribution map