Wow. What a tricky question. The 11' Rd nearly killed my 12' trimac mix, cowered the 7" midas, 9" texas, 8" managuense. My 4" grammodes rules over the similarly sized convicts, sajicas, and A. Lyonsi's. The a. amarillo battered the same sized green terror when I took out the divider for cleaning. Overall, the red devil takes the cake.
I think my thread on my Convict kicking ass and taking names should say it all as far as I'm concerned. However...
My big Midas is a %^&ing bad ass. He attacks EVERYTHING. Whether that be my magnetic glass cleaner, siphon, plastics plants...
Hell, there are nights I can hear him throwing a fit in the tank and wake up to the heater laying on the bottom, filter intake floating around and all the decor strew about like an atomic bomb exploded.
He entertains himself by picking up rocks (about 3"s wide you can see one in the corner of the tank in one of the pictures) and spitting them at the glass. All night I hear this... "tink"...."tink"..."tink"... over and over again. I almost think he's trying to break the glass and escape.
male flowerhorn, however my dempsey (an inch or 2 shy of my FH) beat the crap out of him a few times, but my dempsey in general was no where near as aggressive as the flowerhorn
i always thought my silver dollars could outrun cichlids, but one day my flowerhorn chased him into a flowerpot and ripped his eyes out.
My reddevil is the meanest cichlid i currently own his name is tush hog and he will be 2 years old in september he is 9-10" long and is the definition of glass banger he knocks the glass top up with his hump and bites at anything that comes within 3 or 4 feet of his tank. The first couple pics are old when he was smaller and not as mean but the last 2 are only a couple weeks out.