^ I have heard this about the Nile tilapia also, I don't see them in the shops here very much though, maybe because they're not as pretty as buttikoferi.
Dovii for sure.I have a F1 Butti and all my friends have Butti's to and if you supply them with a big enough tank so they can go about there business they aren't that bad.
i once made the mistake of adding my dovii to my butti's tank, both were about 11-12 inches. it looked like they were going to get along but when i woke up the next morning, the butti was mangled to death so dovii for the win
My vote would be a male dovii as being the most aggressive in my experience. However the male Butt is very close.
In large tanks like mine both mellow out and once dominance is established years go by without much aggression.
Placed back into smaller tanks under 500 gallons both of their aggressive natures return.
My smaller Dovii male in the 52 (17") was always more aggressive than my 22-23" male in the 15. The bigger Dovii died in 2009 after being killed by the 26" black shark (Not a fair fight as the old Dovii was very long on the tooth..pun intended).
The smaller Dovii is still doing well in the the 52.