Acanthuriformes

Acanthuriformes is an order of ray-finned fishes comprising several families of reef-associated fishes, most notably the surgeonfishes (Acanthuridae) and the moorish idol (Zanclidae). The circumscription of Acanthuriformes has varied over time; while once placed within Perciformes, most contemporary classifications recognize it as a distinct order containing a suite of related families.

They commonly have laterally compressed bodies, small mouths with rasping teeth, and a two-part caudal peduncle spine in many surgeonfishes used for defense. They typically possess a continuous dorsal fin and anal fin with a slight body depth; coloration is often bright and variable, especially in reef environments.

Found in tropical and subtropical oceans worldwide, with high diversity in the Indo-Pacific; most species are associated with coral reefs or rocky substrates, where they graze on algae and detritus.

Diet mainly herbivorous, scraping algae from rocks and corals; some species consume small invertebrates. They may form schools during the day and occupy crevices at night; juveniles often display different coloration.

Most species are broadcast spawners, releasing eggs and sperm into the water column; pelagic eggs and larvae drift with currents before settlement. Some species are popular in the aquarium trade and reef fishing, and several face overfishing or habitat degradation.