After looking at this picture a little more, I am almost positive that is a cubicus. You should do some research on these fish. They are very poisonous. If stressed they will secrete poison that will kill every fish in your tank, including him. I know this for a fact. I had my cubicus for several years. I wanted to put him in a better environment because he was in a tank with quite a large niger trigger that picked on him. After acclimating him to the new tank I put him in - within 5 minutes I had lost 2 purple firefish. I immediately removed him and started a water change. Did quite a large one but within an hour had lost my hippo tang - I really thought the scooter blennie would make it but by morning he was dead too. It didn't hurt any of my coral, shrimp, starfish, snails or hermits and the clowns lived. I think the clowns lived because they are used to poison of anemones. I don't know - just thinking that may have something to do with it. But my point is, if this is a cubicus they are very neat fish and have a great personality but if you are not extremely careful with them they can make you very sorry you bought them. I will never again have another poisonous fish.