johannis are usually very agressive I have heard... I agree many tangs are peaceful toward other types but they are agressive enough to hang and not get picked on which is good... sometimes it can depend on the individual fish though as said above about their johanni being passive, I have 3 zebra males that never fight eachother or the other fish and are even with one female and they dont even harass her hardly. The Ob zebra is the biggest and he is the peacekeeper he actually breaks up fights when they occur it's very unusual though as most zebras are mean lol
red zebras and kenyi are the most agressive malawi I have had. My johanni and yellow lab don't even pick on baby convicts. But it does depend on the fish. This is just generalized.
However from the fish I have here and the fish at work, red zebras and kenyis are mean,lol
Though other many tangs are a close second.
E.g. Asprotilapia leptura, Enantiopus melanogenys, Xenotilapia spilopterus and quite a few other Xenotilapia.
Comparatively speaking is there such a thing as a peaceful Cichlid.
Mine seem to be happiest fornicating or fighting.
My definition of peace is nobody got hurt or eaten.