I have a 65 gallon tank that inhabits about 15 fish including angelfish, mollies, guppies, platties, neon tetras, 1 mystery snail, and 2 algae eaters. I have 4 adult angelfish. I recently just bought one because two of the three were fighting with one I bought at a different store about 2 days after I bought the first 2. I heard the do best in 3s or 4s. Since the were biting at that one I thought if I got one more maybe they would each have a friend and not bother the others. However, I was wrong. They fight among each other all the time. They nip at each other and chase them around. They only mess with each other. The newest one is the meanest of them all. I was wondering if it was ok to place him in his own tank since he is aggressive. I have a 10 gal tank with nothing in it and thought it'd be perfect for him alone. Is there anything else I can do about them fighting with each other so much?