My old mayan cichlid "cichlasoma uropthalmus " was aggressive as hell nearly killed a jack dempsey 3'' bigger then him and tried to take on my old jaguar cichlid he actually might have won if i hadn't sold him very underestimated cichlid
My male con - he took down jaguar cichlid i use to have, the jag was an adult, so was the con.
He ripped out his eyes are demolished him, the con destroyed a firemouth I also use to have and he absolutely battered my Jack dempsey. I had a full grown flowerhorn, he Ripped its eye out and it died within seconds.
He wasnt even breeding at the time, they all picked fights with him.
From my personal experiences of cichlids that I own or have owned. I would have to say exCichlasoma Beani (pound for pound). I haven't seen any fish flip out like them yet. Although my 1st Umbee is on its way next week so my experiences are still increasing.