Tag Archives: Acanthurus triostegus

Convict Surgeonfish

Acanthurus triostegus

With a very wide distribution along the tropical coastlines of the Indo-Pacific, stretching from South Africa to California, the Convict Surgeonfish, or Convict Tang, is one of the most numerous and well-known of its family. Apart from the six obvious stripes on its body, its name comes from the sharp, scalpel-like spines on either side of the base of its tail that it keeps retracted until it needs to deploy them in self-defense.

Living along shallow reefs (usually less than 90m deep) and rocky shores, and even in harbours, the Convict Surgeonfish feed exclusively on algae they scrape from the rocks. Young fish are often seen in rock pools at low tide. They’re social fish, living in schools numbering from a few individuals to several thousand. They breed during full moon in late winter and spring. Most grow to only about 17cm in length, though some specimens may grow to as much as 27cm.

Convict Surgeonfish are often seen in home marine aquaria, but suffer high mortality if they cannot be provided with copious amounts of fresh seaweed. According to the IUCN this species is of least concern.