ok, this is all going to depend on YOUR SPECIFIC FISH. not all fish have the same temperment. My Male jag is currently 15.5 inches long. he was raised from about 1 inch long, during he life he has lived with (not all at once) 2 oscars , male red devil,12" male rtm, 2 jds, grammodes (4in), 11in male festae, ornate and sengalas bichers oh and a 9in green severum. Hes chill baby!! the only ones who got a whoopin were the oscars, but they fought back. and although i would swear he was going to break their jaws..there was no serious injuries and no deaths. Hes super easy going now, only would kill a goldfish....but i dont give him feeders anymore. hope this helps