The Blue Damselfish (Chrysiptera cyanea), also known as the Blue Demoiselle or Blue Devil, is a species of damselfish found in the wide Indo-West Pacific.

Distribution and Habitat

The Blue Damselfish is found in the Indo-West Pacific. It inhabits reefs and lagoons.

Physical Description

This fish reaches 8.5 cm (3.3 in) in length. It is bright blue in color. The male has a yellow snout and tail, and the female and juvenile usually lack yellow but have a black spot at the base of the back edge of the dorsal fin.

Diet and Feeding

The Blue Damselfish feeds on algae, tunicates, and copepods. In captivity it accepts a varied diet including flakes, brine shrimp, mysis shrimp, and frozen preparations.

Behavior and Reproduction

Male and female pair up for breeding and the male guards and tends the eggs. This species is very aggressive. A matched couple often attacks any same size fish approaching its breeding territory.

Aquarium Care

It requires a tank of at least 20 gallons with abundant live rock for hiding. It is considered reef-safe. Due to its aggressive nature it should be kept singly or as a mated pair.

Conservation Status

Classified as Least Concern by the IUCN Red List.