That is a jewel. If you get other fish in the tank that test his dominance he will brighten up with color. If you put another jewel in there make sure they are the same size. I had my big boy Clifford destroy 2 other jewels I put in my tank because he was a lot bigger than them and he didn't like the competion so he killed them off. So if uoure looking for tank mates make sure they are different All the other breeds of fish that I have that are smaller are perfectly fine with him! (My smaller peacocks,mbunas and my acei cichlids ) He is about 7inches and my small guys are about 3 inches or less..