Its a 55 gallon tank, he is getting a variety of different foods from frozen, flake, pellets, and he even goes for the sea weed on the clip so he stays well fed. Nothing chases him, he pretty much dominates the tank. He seems healthy and is always out swimming around the whole tank. He seems to change the most right after he eats a lot and then he goes and sits in the rocks for about 15 minutes or so.