Powder Blue Surgeonfish-Facts and Photographs

Powder Blue Surgeonfish (Acanthurus leucosternon) is also known as the Powder Blue Tang.

The Powder Blue Surgeonfish (Acanthurus leucosternon) is also known as the Powder Blue Tang. The species gained international fame in the animated children’s film by Pixar, “Finding Nemo” where one of the central characters Dory was a Powder Blue Surgeonfish. They are not common on the Tanzanian coast but on occasion there are fairly large numbers in an area.

Members of the Acanthuridae family have a retractable razor sharp spine on either side of the caudal area. They obtain their name Surgeonfish from these blades.  The blades are used for defense and possibly in territorial disputes and can inflict significant damage. The blades are reported to contain toxins but there seems no scientific evidence for this.


The Powder Blue Surgeonfish has a disc shaped body that is laterally compressed. The mouth is low on the body and the eye is set high and quite far forward on the body giving the fish a good field of view and protecting the eyes while feeding. The head has a black mask across the top and white below. The bulk of the body is a beautiful powder blue colour and the dorsal fin is yellow ringed in blue, the base of the pectoral fin is yellow and the anal fin is a light blue.

On the caudal area there is a yellow patch and the caudalfin is white with black edging and a blue line down the terminal end. They are extremely attractive looking fish with their bright contrasting coloration. They grow up to 23 cm in length but around 18 cm is more common in the wild. The juveniles pictured further below in the post are similar to the adults in coloration.

Powder Blue Surgeonfish (Acanthurus leucosternon) is also known as the Powder Blue Tang.


The Powder Blue Surgeonfish is not that common overall in Tanzanian coastal waters. At certain times of the year however the population seems to concentrate in certain areas giving one the impression that there are greater numbers. Usually they are seen solitary but occasionally are seen in small groups of three to five fish. On other occasions, usually in the summer months they are sometimes seen in very large numbers feeding together.This could be mating related.

They seem to prefer reef flats with abundant algae growth but will also occasionally be seen over rubble areas. Powder Blue Surgeonfish are active fish, always on the move and always feeding. They are more common in the 12 to 20 meter range. The juveniles are often seen in the shallows on protected reefs from 1 to 5 meters.

Acanthurus leucosternon 3


Powder Blue Surgeonfish are found across the Indian Ocean from South Africa north up the coast of East Africa and across to Christmas Island and the Cocos Keeling Islands.

Acanthurus leucosternon 2


The Powder Blue Surgeonfish are grazers and feed on benthic algae.


Group spawning takes place with the females releasing spawn into the water table and the dominant male fertilizing the eggs. Once the eggs hatch the larvae go through a planktonic stage before settling down.

Acanthurus leucosternon 1


Powder Blue Surgeonfish are commonly kept in aquariums and are sought after by some collectors. They require high quality clean water that is well oxygenated. They are fairly easy to feed but a big part of their diet should be algae in one form or another to keep them healthy.

Because of their territorial nature they should not be kept with fish with a similar shape or diet. Great care should be taken when moving them as their blades can easily snag in a net or worst case pierce a bag.


Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Acanthuridae
Genus: Acanthurus
Species:A. leucosternon