My Fahaka is much more aggressive then my mbu, I have tank mates with my mbu, but none with my fahaka, and she's only 3 inches verses my mbu who is 10 inches.. she won't even let you have your hand in there for too long without trying to bite onto it!! She is awesome though.. she will get about 12-16 inches depending on the fish. Fahaka's can be in a 120 for their whole lives.. but of course bigger is better