I read (dont know how factual this is) that piranha will only attack from the back of a fish, never head on. That they actually look for the fishes eyes and intentionaly good after the other end. Now hearing that kinda makes sense why so many people have kept oscars (I beleave there red tail) in with p's. these certain oscars have a redish circle on there back fin that looks like an eye on both sides. thus the piranha don't know with end to attack. humm does anyone know if this is true???? I had my snake head in my tank with my p's all day yesterday and they left him alone. then today I herd something and turned around and they were all goin at it. so I removed the snakehead from the tank and put him back. now missing his fin.