Indo-Pacific: throughout the region except for the seas around the Arabian Peninsula. Eastern Pacific: lower Gulf of California to Panama, including the Revillagigedo, Cocos, Clipperton, and Galapagos islands.

Body olivaceous gray, with 4 vertical stripes (1 stripe on head across the yellow eye; 1 on caudal peduncle); shading to white ventrally, often with a sharp line of demarcation. Sharp, forward-pointing, erectile spine on each side of caudal peduncle which folds down into a groove. Scales minute. Teeth with denticulations on sides and top. Gill rakers 18-22 in anterior row, 19-24 in posterior row.

Occur in lagoon and seaward reefs with hard substrate; young abundant in tide pools. Benthopelagic. Often feeding near freshwater run-offs where certain algae grow on rocks that are grazed. Occasionally form schools; feed on filamentous algae in large aggregations. During spawning, clouds of eggs and sperm are preyed upon by eagle rays which are often present during spawning. Form spawning aggregations.