Powder blue tang

Lore & Background

The powder blue tang has an oval, laterally compressed body that can reach an average length of 23 cm. Its sides are blue, the dorsal fin and base of the caudal fin are yellow, the head is black, and the mouth, throat area, anal and pelvic fins are white. The pectoral fins are transparent with yellow reflections. The intensity of its blue color indicates the fish's health. It does not undergo color changes as it matures. This species is found in tropical waters of the Indian Ocean, inhabiting shallow and clear coastal waters always associated with a reef. It prefers flat top reefs and areas along seaward slopes. The powder blue tang is diurnal, solitary, territorial, and aggressive with other surgeonfish. It is herbivorous, eating mostly benthic algae. When food is plentiful, it may feed in shoals, but in times of scarcity, it competes individually for food. It may use its surgeon's scalpel as a defensive weapon.

Reader's Guide

Acanthurus leucosternon is a herbivorous fish that feeds mostly on benthic algae, playing a role in controlling algal growth on reefs. It is diurnal and typically solitary and territorial, especially aggressive toward other surgeonfish. When food is abundant, it may form feeding shoals, but under scarcity it competes individually. It possesses a sharp, erectile spine at the base of the tail, known as a surgeon's scalpel, used for defense. In the aquarium trade, the powder blue tang is rarely harvested for anything other than the marine aquarium industry. It is a commonly sold fish that is moderately difficult to care for, though its popularity is exceeded by the regal tang and yellow tang. It is very prone to Cryptocaryon irritans.

Did You Know?

• Its specific name leucosternon combines Greek words meaning 'white' and 'breast', referring to its white chest.
• The fish has a 'surgeon's scalpel' — an erect part of the spine at the base of the tail — used for defense.
• The intensity of its blue color shows whether the fish is healthy or not.
• It does not undergo color changes as it matures, unlike some other tangs, surgeonfish, and unicornfish.