My experience with peacocks and aceis has been totally weird and opposite. When I was switching the mbuna tank to peacock I still had a couple of aceis, rusty, afra and a yellow lab in it, afra and rusty showed some aggression, but nothing major, I still took them out to make room for more peacocks, thinking that aceis and labs would be a much safer way to go. Well when I got to the blue selection of peacocks and dropped the ngara flame tail and a stuart red shoulder in, the aceis went crazy, there was non stop chasing and nipping from aceis, after about a week of this they went back to the lfs for more trade ins. In the end the only mbuna left was an adult yellow lab, who for the most part kept to himself.