A colourful and common sight on the Great Barrier reef is the surgeon fish, like the yellow fin surgeon fish pictured above. The distinctive characteristic of the family is the spines, one or more on either side of the tail. Both the dorsal and tail fins are large, extending for most of the length of the body. The small mouths have a single row of teeth used for grazing on algae.
Surgeonfishes sometimes feed by themselves, but they are also often seen traveling and feeding in large colourful schools. It has been suggested that feeding in schools is a mechanism for overwhelming the highly aggressive defense responses of small territorial damselfishes that vigorously guard small patches of algae on coral reefs.
Most species are relatively small and have a maximum length of 15–40 cm (6–16 in), but some members of the genus Acanthurus, some members of the genus Prionurus, and most members of the genus Naso can grow larger, with the whitemargin unicornfish (N. annulatus), the largest species in the family, reaching a length of up to a meter (3,3 ft). These fishes can grow quickly in aquariums so it is advisable to check the average growth size and suitability before adding to a marine aquarium.