Chrysiptera cyanea species is native to the Indian and Western Pacific Oceans, usually its been named as blue damselfish or the blue devil or the sky-blue damsel. It is one of the most selling fish when it comes to beginner tanks. Shiny blue scales tend to shine under the reef lighting. 
The Female Blue Damsels are completely blue and on the other hand males, have an orange tail and are commonly called as the Orange-tail Blue Damsel.
Blue Damsels are hardy, has a life span of 5 years or longer in a clean mature tanks. Small in size and they usually grow about 3 to 4 inch’s. They defend a small territory for themselves. If threatened they have the ability to hide in small holes in the rock and change its color to complete black. They return to its blue color in a matter of seconds once the threat has passed. They have a life span of 5 years or longer in a clean mature tanks.
The blue damsel plays the game of hide and seek for second it will be swimming across the tank and in the other moment its gone inside the rock work. Catching a blue damsel in matured reef is a tough task as they tends to hide and swim in speed.
For a damsel dominated tank, suggestion is to have lot of rock work so that they don’t fight between themselves. Avoid fish which is smaller is size compared to the blue devil, it will just end up harassed by the devil.We to started with the blue damsel and some other fish few year back, it was just wonderful to look at the devil at its acts. The blue devil would displace sand from the bottom of the rock work with its tail for making room for hiding. Would only show its face as if its checking for the threat. At night time they switch color to complete black.
They are aggressive eaters and can come pretty close to your hand when feeding, they would eat flakes, pellets and other frozen fish food. They are relatively cheap compared to other marine specimens which works on the pocket and the hobby.
