I think the get a bad rap for the aggression. i have a big solo fish (about 12 inches) in a mild cichlid community. Sevs, geos, datniod,rays/ No problem it has grown up in the tank with a lot of the fish but even additions have no issue. The parrot is the boss of the tank and occasional bumps a fish here or there but no damage and honestly only really show aggression is other fish are fighting. One of my favorite cichlids and i tell everyone if you have the chance to own one go for it!!!
here is mine
View attachment 943921