Acanthurus nigricans (Linnaeus, 1758)
Whitecheek surgeonfish
Acanthurus nigricans
photo by Randall, J.E.

Family:  Acanthuridae (Surgeonfishes, tangs, unicornfishes), subfamily: Acanthurinae
Max. size:  21.3 cm TL (male/unsexed); max. reported age: 34 years
Environment:  reef-associated; marine; depth range 1 - 67 m
Distribution:  Eastern Indian Ocean: known only from Cocos-Keeling Islands and Christmas Island. Pacific Ocean: Ryukyu Islands and Great Barrier Reef to the Hawaiian Islands and French Polynesia (excluding Rapa). This species has crossed the Eastern Pacific Barrier to the Revillagigedo Islands, Cocos Island, Galapagos Islands, and the coast of Mexico.
Diagnosis:  Dorsal spines (total): 9-9; Dorsal soft rays (total): 28-31; Anal spines: 3-3; Anal soft rays: 26-28. A horizontally elongate white blotch directly below eye. No orange band in outer part of dorsal fin. Caudal peduncle black except for yellow edge of socket and sheath of peduncular spine. Base of pectoral fin black (ref 9808).Gill rakers on anterior row:17-19, on posterior row:18-20. Description: Characterized further by blackish or dark grey body color; white patch below eye; white ring behind mouth; base of dorsal and anal fins with yellow zone that gradually widens towards rear part of fins; caudal spine yellow; caudal fin yellow with submarginal band; caudal spine length 2.5-3.0 in head length; greatest depth of body 1.7-1.9 in SL (Ref. 90102).
Biology:  Adults inhabit hard substrate areas of clear lagoon and seaward reefs from the lower surge zone to at least 67 m and feeds on filamentous algae. Solitary or in groups (Ref. 90102). Monogamous (Ref. 52884, 48637). Benthopelagic (Ref. 58302). Small juveniles shy among large corals (Ref. 48637). Territorial species. Common throughout Micronesia and hybridizes with the rare A. achilles. Size of metamorphosis from the postlarva stage to juvenile is 5.5 to 6 cm (Ref. 9267).
IUCN Red List Status: Least Concern (LC); Date assessed: 04 May 2010 Ref. (123251)
Threat to humans:  harmless
Country info:   

Entered by: Capuli, Estelita Emily - 15.07.92
Modified by: Torres, Armi G. - 31.01.18
Checked by: Garilao, Cristina V. - 08.06.95

Source and more info: For personal, classroom, and other internal use only. Not for publication.

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