Found in areas of coral, rock, or rubble of lagoon and seaward reefs. Benthopelagic. Adults usually in small groups. Juveniles in shallow rocky reefs, sometimes in small aggregations mixed with other acanthurids of similar size. Feed mainly on leafy brown algae (Sargassum and Dictyota). Sometimes in large aggregations. Very seldom poisonous. Pair-spawning has been observed. Most are algae eaters and keep the reef from getting clogged with coral-smothering algae. While edible, they tend to taste a bit like the seaweed they diet on. They are also called surgeon fish due to the sharp, extensible knife-like spines on their tail.