mine was cool at 6 inches, till a pike bit him in the face,, thats when the switch was turned on!!!! i cant turn it off now,,, 1 year later he's in his own tank and tries to attack me thru the glass,, hes a bit over 7 inches now and tooled on my jd real bad, killed the pike, sent a parrot into permanent hideing and beat his mate to the point i had to bring her into my lfs, hes the most aggresive fish i have ever seen,
if you keep him around friendly fish there ok, once they are mature and get cornered, they flip hard!
good luck