The Blue Devil available in a pet store may often be a juvenile that has not yet come into its adult coloration. As they mature the males develop yellow-orange tail colors as you can see in the picture above. Females will gain a black spot at the base of the hindmost dorsal ray.

As they mature many damselfish are noted for becoming rather aggressive and are best not kept with smaller or overly passive tank mates. This species is no exception, it is rather territorial and somewhat aggressive. Specimens of this species can be risky if kept together for they may seriously fight causing severe damaged or death.

Providing a rock/ coral decor that has many nooks and crannies for hiding and retreat will help avert aggression. These can possibly be kept in groups if you are careful to have a good male to female ratio and keep a close eye out for trouble. In the wild, there will be several females to one male.

Scientific Name : Chrysiptera cyanea

Common Names : Blue Damselfish, Blue Devil Damsel

Care Level : Easy - although it can be a very hardy fish and some use them to cycle their tanks, we don't recommend this practice and it's easier and quicker to cycle a tank with live rock.

Size : Up to 2.5 inches (6 cm)

Life span : 5 years or longer

pH : 8.1 - 8.4

Temperature : 75°F - 82°F (25°C - 28°C)

Specific Gravity : 1.020 - 1.025

Carbonate Hardness (dKH) : 8 - 12°

Origin / Habitat : Indo-Pacific, Australia, Pacific

Temperament / Behavior : Can be very aggressive with other fish that encroach upon their territory. Even much larger fish can get harassed when swimming past their territory. Use caution when introducing new tank mates in a tank already populated with blue devils.

Breeding / Mating / Reproduction : This fish has been bred in the home aquarium.

Tank Size : 30 gallon (114 liters) minimum

Compatible Tank Mates : Use caution when selecting tank mates. Avoid keeping them with other damsels but if you do, introduce at the same time to limit territorial aggression. May harass other tank mates that come into their territory.

Fish Disease : Saltwater Fish Disease - Diagnose, Symptoms and Treatment

Diet / Fish Food : Omnivorous, try to give them a variety of marine foods. They should accept vitamin enriched flake foods, frozen and live foods.

Tank Region : Usually stays close to its chosen territory in the live rock or any other tank decor that can provide shelter.

Gender : Females have the black spot on the dorsal fin, whereas males may not have the black spot.

Similar Species : Damselfish - Green Chromis, Blue Chromis, Yellow Tail Blue Damselfish