Before deciding on a new home, if you have some time (and patience), you can give some behavior therapy a try. I am guessing the white one is the abuser or is it the other way around?
Anyway, get a clean plastic mesh laundry type basket- the dollar store has ones that are 1 to 1.5ft deep and around. If its a small fish, you can try deep plastic pasta strainer/colander. Place it in the top of the tank. Anytime you see bad behavior, place the bad boy in a timeout in the basket/colander for few hours. Just make sure you keep an eye on him because he may try to jump out or injure himself. once he is well settled, release him. The second he starts again, repeat. And keep repeating. Some fish figure out this isn't any fun in a few days. Others it takes much longer. In a few rare cases, hormones can not be stemmed but generally it helps to curb bad behaviors. Good luck!
