Yeah, mine have not been getting along well since my third angel died. The two remaining were the smaller of the three, and one has ben chasing the other... I'm not sure how much chasing is still going on right now (I'm at college), but I'll probably have to return the black one (I like the other better). If yours are doing damage to each other, you'd do best to remove one or the other, or else the weaker one will be terrorized and pestered to death.