my oscar rules the tank without aggression.Ifanybody challenges him he opens his mouth as wide as he can and shakes his butt,dumbfounding his opponant (usually the JD) and the runs away and looks for something to stuff his face with leaving my JD to ponder what just happened and then go back inside his cave.....works everytime.....my JD stays in his cave and my Oscar has free roam of the tank.

