IME they are all a**holes after they reach about 7 or 8 months old. I would highly highly recommend against getting any damsels unless for some reason they are your must have fish. They are next to impossible to remove without breaking down the tank. They become absolute a**holes the bigger they get. I have seen them as big as 6 inches. They are very territorial. I have owned yellow tail, yellow belly, dominoe, and those electric blue ones........2 of each. They are all gone and I will never buy one again. The only reason I got them was at the (bad) recommendation of my LFS when I first setup my tank. Prior to doing all of my research..........