i like mine and he is about 9 inches. He keeps fish away from his perch of driftwood but otherwise didnt bother other fish. I have a green terror (about 8inches) and a red tail giant gourami (about 14inches) in the tank with him and he will chase the othe two away if they get too close.
I also have bichirs in the tank and i have recently suspected him of eating the slime coat from the undersides of my bichirs and i am still evaluating the situation to see if that is actually happening. Sometimes the bichirs will float or hang halfway off of the driftwood and the catfish will act like the bichir is part of the driftwood and hang upside down under the bichir.
not sure if he is actually eating the slime coat, but he is certainly biting their fins and undersides and they hardly react to it. i think i may have overreacted to the slime coat issue and i think it is just biting my prized bichirs...
if anyone wants to pick up a free one though you can have him