I am going to vote from my tank experience and say Red Devils, Doviis, Trimacs, Umbies are the most of aggressive and it all depends on the character of the fish you have which is the Baddest, I have a female red devil that has taken on the lot of them and still currently resides alone. I have tried and failed to put her in a communal atmosphere.My Male dovii is too imporatant to me to find out if he could survive with Dorothy my RD, she is old as my eight year old son>