The Yellow Tail Blue Devil, Chrysiptera cyanea, has many different common names including the Sapphire Devil, Yellowtail Blue Devil, Cornflower Segeant-Major, Cornflower Sergeantmajor, Red Tail Australian Damsel, Sky-Blue Damsel, Blue Damsel, and Orangetail Blue Damsel. They thrive best in tanks with plenty of live rock for it to hide. They have the unique ability to change the color of their body is response to external stimuli when it feels threatened. The Yellow Tail Blue Damsel is generally peaceful but as it matures can exhibit some amount of territorial behavior, so if multiple individuals are desired ensure you have a large enough tank to house them. Overall, the Yellow Tail Blue Damsel is incredibly hardy and makes an excellent addition to almost any home aquarium.