Description:

Dorsal spines: 8; Dorsal rays: 27-28; Anal spines: 3; Anal rays: 22-29.
Small, full-bodied, laterally compressed surgeon fish. Mouth somewhat protruding. Up to 17 teeth in upper jaw and 22 in lower. Dorsal profile of snout concave. Caudal 
fin of adults lunate. Adults dark brown but capable of quickly changing to light tan. A broad black band extending from chin and throat, across most of the opercle, 
to upper end of gill opening. A black band extending dorsally from pectoral fin axil to upper end of gill opening. Lips blackish. A transverse white band on chin 
adjacent to lower lip, and another in black area on throat. Caudal spine socket broadly edged with black. Caudal fin brown with the pure white margin. Juveniles mimic 
the angelfish Centropyge eibli.

Maturity: Lm unknown. Range unknown. Max length: 25.0 cm TL.
 

Occurs in shallow lagoon and seaward reefs, in areas of mixed coral, rock or sand (depth 2-30m), with an apparent preference for deeper and more sheltered waters, 
frequently over sand and rubble bottoms. It is classified as a detritivore. Juveniles of this species resemble Centropyge eibli. 
 

This species is not protected or subject to fishery regulations. It is caught in the fish trap fishery. Its relative abundance in the catch is hard to assess due 
to its general similarity to A. nigrofuscus and C. binotatus. 
 

Abesamis, R. et al. (2012). Acanthurus tristis. The IUCN Red List 2012: e.T177998A1516342. http://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T177998A1516342.en. (09/06/19).
Froese, R. & D. Pauly. Eds. (2019). FishBase. https://www.fishbase.se/summary/12782# (09/06/19).
Randall, J.E. (2001). Surgeonfishes of Hawaii and the World. ISBN: 1-56647-561-9

Nevill, J.E.G. (2019). Acanthurus tristis, Blackcheek surgeonfish. Seychelles Seatizens. www.seatizens.sc. https://seatizens.sc/species/acanthurus-tristis-randall-1993/ (edited 15/06/22)