People have always said that cichlids are very intelligent for fish. I have even heard that oscars can learn tricks. So I figured that if they learn tricks they can learn other things such as discipline. what i do is I thrust a finger or whatever I have in my hand right at the aggressive male whenever I see him chasing someone else . It probably means and changes nothing but for the moment but I do it whenever I see my dominant male beating up on my other males. they're still alive