ornates seem to be the meanest of the bichirs. i have one that is 15 inches and sometime tries to mess with my 13.5 in jag but the jag just pushes him away whenever he wants. it would be very unusual for a bichir to do any real damage to another fish unless the bichir thinks it can swallow them. ive seen vids on bichirs deathrolling pieces of fish fillets that are thrown in the tank but nobody has ever shown a vid of a bichir grabbing another big fish and ripping it up. just not going to happen.