I have a 60g tank and in it I have 1 male convict, 2 females, one 9'' female red Texas cichlid, 1 male, 1 female green terror, 2 red Texas/green terror hybrids, 3 key hole cichlids, 3 Nicaragua cichlids 2 guamies, large plec and a red tailed shark and a talking cat fish and I never get any fighting they all are really tolerant of eachother, when the convicts breed they get a bit territorial but not too bad, oh I've also got a 20g with about 80 6month old convict fry
Most south American cichlids get on with eachother, defo don't mix African with American