The Blue Devil Damsel (Chrysiptera cyanea) is a hardy, brilliant blue fish. The only significant marking is one small black spot by the rear of their dorsal fin. Adult males from some regions may develop orange on their tails and undersides.
Damsels and chromis both come from the Pomacentridae family, which they share with Clownfish, a close relative and another very popular group of aquarium fish. Their temperament can range from very peaceful to quite aggressive and territorial. Chromis (fish from the genus Chromis) tend to be more peaceful than the rest but can also be more delicate. Other common genuses of damsels include Amblyglyphidodon, Chrysiptera, Dascyllus, Neoglyphidodon, Pomacentrus, Stegastes and others.
These fish are generally not picky eaters. In the aquarium, they will usually feed on flakes and pellets but should also be given fresh or frozen algae and meaty foods like brine shrimp, mysis shrimp, planktons, krill, shrimp, scallop and similar items.
Damsels can become very territorial as they become established in the aquarium. Some species will defend their territory especially aggressively; use caution when stocking the aquarium since their small sizes can be deceiving; mature or established damsels may pick on smaller or weaker fish or on new arrivals. Some damsels retain the same appearance throughout their entire lives while others undergo a radical color change as they mature from juveniles to adults. A few may get more colorful as adults but most change from very colorful juveniles to bland, more subdued adults.
I agree totally with the other poster. I bought two of these along with a Cardinal fish whenever I first started my 55 gal tank. In one week, one of the Devils had killed the other and the Cardinal was so scared to come out, it starved to death. This little blue guy set the tone for my tank from then on out as you cannot catch them, and the are VERY aggressive to ANYTHING in the tank. I now have the Devil, a BW Clown, a Falco Hawkfish, a Coral Beauty, a Fuzzy Dwarf Lionfish, and a Purple Lobster. Any fish added to the tank must be very brave and able to defend itself against this small jerk face. I won't ever buy one again, as now I cannot buy any tangs or peaceful fish, and am setting up another tank for nice fish because of it.
There's a reason it has devil in the name 5/31/2012
Reviewer: Sean Fanning
These fish are EXTREMELY territorial. If you do get one you CAN NOT have fish the same size or smaller because it will harass them continuesly and they will even harass larger fish. There's a reason there is the word devil in their name!