Surgeonfishes and Tangs (Acanthuridae): Reef Grazers with Blade-like Caudal Spines

Description

Individuals in this family are laterally compressed and often display vivid patterns and hues. A distinctive feature is a movable, scalpel-like spine located on the caudal peduncle; this structure can be used in defense or during fights between conspecifics. Some species, known as unicornfishes, develop a horn-like protuberance on the forehead. Sizes range from small to moderately large depending on the species.

Distribution and habitat

Acanthurids are marine fishes found mainly in tropical and subtropical seas around the world. They are especially common around coral reefs, where many species graze on algal growths on rock and coral surfaces, although some occur over rocky reefs or in seagrass beds.

Diet and behaviour

Many surgeonfishes are primarily herbivorous, cropping algae and helping to control algal cover on reefs; others have more varied diets that include detritus or small invertebrates. Reproductive behaviour varies, but numerous species release eggs and sperm into the water column and produce planktonic larvae that disperse with currents.

In captivity

Because of their striking appearance, several acanthurids are sought after for aquaria. Successful care usually requires large tanks, appropriate grazing foods, and attention to water quality—some species are highly active or territorial and are not suited to small home aquariums.

Taxonomy and role on reefs

• The family contains a number of genera and roughly eighty to ninety living species, depending on the source and recent revisions.
• As herbivores and omnivores, surgeonfishes play an important ecological role by grazing algae and contributing to reef health and resilience.