Acanthurus

Acanthurus is a genus of marine ray-finned fishes in the family Acanthuridae, commonly known as surgeonfishes or tangs. Members of the genus are herbivorous grazers that inhabit coral reefs, rocky coasts, and seagrass beds across tropical and subtropical oceans, with the greatest species diversity in the Indo-Pacific.

Typical Acanthurus species have laterally compressed bodies, small mouths with beak-like teeth suited to grazing algae, and a distinctive pair of scalpel-like spines on the caudal peduncle used for defense. They are usually active during the day and often form schools or territorial groups around feeding sites. Coloration and patterns can vary with age, sex, and aggression, and many species display striking color changes during reproduction or social interactions.

Distribution is broad, but most species occur in warm waters of the Indian and Pacific Oceans, with several Atlantic species also recognized. Notable examples include Acanthurus chirurgus, known from the western Atlantic, and other Atlantic representatives such as A. bahianus. Across its range, the genus is tied to reef ecosystems and coastal habitats where algae are abundant.

Ecology and behavior: Acanthurus species play a role in controlling algal growth on reefs, contributing to coral‑reef maintenance. They are typically diurnal, migrate in response to feeding opportunities, and may form mixed-species schools.

Conservation and human interaction: several species are popular in the aquarium trade and fisheries; overfishing and habitat degradation can affect local populations. The name Acanthurus derives from Greek acantha (thorn) and oura (tail), referencing the sharp tail-spines characteristic of the group.