Dorsal spines (total): 9; Dorsal soft rays (total): 25-28; Anal spines: 3; Anal soft rays: 23 - 26. Color in life dark brown without lines on body or spots on head (one phase is purplish grey); horizontal black band behind upper gill opening absent on juveniles <6 cm SL; elongate purple band may be present anterior to dorsal origin; caudal fin brown; outer third of pectoral fin pale. Species with gizzard-like stomach.
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Occurs in clear lagoon and seaward reefs around isolated coral heads. Solitary or in small groups. Prefers sandy bottoms of bays and lagoons rather than the coral reefs like most other Acanthuridae.
Blackstreak Surgeonfish is harvested as food (in some parts of the world) and is a component of the aquarium trade. Harvest is not considered a major threat globally and it occurs in a number of marine reserves in parts of its distribution.
The sexes are separate among the acanthurids (Reeson 1983). Acanthurids do not display obvious sexual dimorphism, males assume courtship colours (J.H. Choat pers. comm. 2010). This species was reported to form spawning aggregations on the Great Barrier Reef (Squire and Samoilys unpub.).