Im pretty sure it was because my 10" Oscar claimed the tank to him self witch is 79g (4ft). First he tryed to kill the other oscar and then i put the catfish in and went for it right away flareing up and chargeing at it. I couldnt keep him in that tank anyway he was just getting to big, one he hit 10" (25cm) he really started to grow, in about 6months he grew another 7"s!!!