Some cats and plecos will work but a mbuna tank is best JUST a mbuna tank lol some people mix the different Malawi cichlids like peacocks and mbuna but that should be tried only after your comfortably with proper husbandry of your fish. I keep an OB peacock with my yellow lab colony and he's the tank boss but I don't have any aggression issues. If they were more aggressive mbuna like auratus, johanni, bumblebees, or mainganos then most likely my peacock would get harrassed to death.