I'm new to Malawi Cichlids myself, have been keeping male peacocks & haps for about six months in my 180gal. Currently have seventeen 3.5"-4" of them in there and the tank is fairly full already for my tastes, don't think I'd want more than that. I just got a 450gal and have forty-four all male peacocks & haps arriving to me next week. I know people overcrowd to spread the aggression but I'm hoping the large sized 450gal will make the difference.