hard one , at one time had top aggressive 12 in one tank with 15 feet of pvc pipe cut into 15 inch tubes no deaths from fighting or sickness 5 years. uhhhhhhh 1 hatian cichlid 2 grammode 3 butikoferi 4 cuban 5 red devil 6 jag 7 wolf 8 umbee 9 black belt 10 green beani 11 tiger mota 12 toss up between istalantus and mayan cichlid. all could be meaner if kept alone at first but u put all together at same size , see more. some cichlids are more aggressive at there breeding stage or maturity 3.5 to 5 inches red devil for example but when older mellower but still territorial fish. i always here jag or dovi or umbee. ha u never over stocked and held it down wit da monsters i guess.my alphas grew bigger they were community smarter and still instinctivly hunters quarrelers and most of all family