The only aggression I see in my 6' (244g tank) is inter species. The bumblebee chases the one other bumblebee, the Kenyi chases the other 3 Kenyi, so on and so forth. But no matter who chases who it all end at the edge of the reef and the pursuer gives up chase for quite a while. But I don't see any other species against species aggression. Only time i do is when I introduce a ne fish, like a pack of dogs they all want a sniff of the new dog it seems like. Other then that if a fish is sick, unless I can get the sick fish out in time which is very hard in this large tank, the sick fish gets recycled, only had one apparently already sick from VetSmart.
VetSmart told me that the best way to keep A. Cichlid aggression down is to keep them in a smaller crowded tank, whey they get along so well in their small 10 gallons they told me. I dont believe that though, as inherently having crowed overstocked fish is a bad thing and the bigger the tank with fewer fish is always the better and healthier in my book.