mI never kept a Red Terror or a Dovii but I hear they are the worst. Of the fish I have kept, male Midas and Flowerhorns were the only fish I had to give their own tank - I tried keeping a 14-inch Midas w/ a 23-inch channel catfish and I had to take the catfish out after a week because of how beat-up he got. Jaguars are surprisingly not nearly as bad as I read most people made them out to be, even on the spawn, at least mine were not, but I'm sure there is a big difference between my 12-inch males and a full-grown 16-incher or more. Even though they don't get very big, my Convicts and Firemouths always swore they weighed 5lbs each...lol
I recently bought my 1st Pike cichlid, I'm guessing a saxitilis but I really don't know what ssp it is and I hear they are rather nasty, so I guess I'll find out soon. I would imagine the Eye-spot cichlids would be the worst by far - at 3 feet +, they have been known for ripping treble hooks right out of the lure-bodies, but IDK if they could stand up to an angry male Dovii.
agree about the tilapia buttekofferi as well...I had one that was only about half-grown and he was in beast-mode 24-7....he would even jump out of the tank and knock the cover around....I could hear him smacking it from 2 floors up!