Acanthuridae

Acanthuridae, commonly known as surgeonfishes or tangs, is a family of marine ray-finned fishes in the order Acanthuriformes. The group includes about 85–90 species in four genera. A defining feature is a pair of sharp, retractable spines on the caudal peduncle, used for defense and giving the family its common name. The body is laterally compressed, with a small terminal mouth adapted for grazing.

The principal genera are Acanthurus, Ctenochaetus, Naso, and Prionurus. Color and pattern are highly variable among species, with some displaying vivid blue, green, or yellow markings that may change with age or mood.

Acanthurids are mainly tropical and subtropical, concentrated in the Indo-Pacific but with representatives in other oceans. They inhabit coral reefs, reef crests, lagoons, and seagrass beds, from shallow nearshore waters to outer reef slopes. Diets are primarily herbivorous, feeding on algae and detritus; some species also consume plankton or small invertebrates.

Many species form small to large schools, particularly juveniles; adults may defend feeding territories. They play a key role in reef ecosystems by controlling algal growth, influencing coral recruitment and reef resilience.

Most species are broadcast spawners with pelagic eggs and larvae, spawning often linked to lunar cycles. Acanthurids are popular in marine aquariums and are fished for food in some regions; they require large, stable tanks with ample grazing opportunities.

Conservation status varies by species; habitat loss, overfishing, and climate change threaten some populations.