Acanthurus nigroris Valenciennes, 1835
Bluelined surgeonfish
photo by Randall, J.E.

Family:  Acanthuridae (Surgeonfishes, tangs, unicornfishes), subfamily: Acanthurinae
Max. size:  25 cm TL (male/unsexed)
Environment:  reef-associated; marine; depth range 1 - 90 m
Distribution:  Indo-Pacific: Aldabra and Seychelles to the Hawaiian, Marquesas and Tuamoto Islands; throughout Micronesia.
Diagnosis:  Dorsal spines (total): 9-9; Dorsal soft rays (total): 24-27; Anal spines: 3-3; Anal soft rays: 23-25. Color drab dark brown; spots on body located at the rear base of dorsal and anal fins. Black spot at rear base of dorsal fin not large, its greatest width more than 2 times in eye diameter. White posterior margin of caudal fin very narrow, its width less than 4 times in pupil diameter. No definite black margin around groove of peduncular spine. Body depth 1.8 to 2 times in SL. Maximum standard length about 20 cm (Ref 9808).
Biology:  Inhabits clear lagoon and seaward reefs; often in areas with mixed coral, pavement, rubble and sand substrates (Ref. 1602). Benthopelagic (Ref. 58302). Occurs singly or in small groups (Ref. 9710). Feeds on filamentous algae, diatoms and fine algal film of compacted sand (Ref. 1602). Relatively uncommon throughout Micronesia; rare on Great Barrier Reef.
IUCN Red List Status: Least Concern (LC); Date assessed: 04 May 2010 Ref. (130435)
Threat to humans:  harmless


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