A whole back I messed up and got a Domino Damsel. I knew they were territorial but he is ridiculous. If he demanded 1/4 of the tank, that would be one thing, but he wants 90%. He was giving my two Chromis heck. So I bought 6 more Chromis, that way he will tire himself out before he tires one of them out as they school. Don't get a Domino as read more later it suggested an 80 gallon or more tank for a single Domino.