Ok, my new black moor seems to be a horrible bully, chases every fish he sees in the QT tank constantly and headbutts them (tankmates are 3 small cories and the little fantail, temp is 75F, 10g tank and the moor is the largest fish at 2.5" total length), sometimes he even goes as far as to bite them. I've got him separated into a floating basket to keep him from stressing everyone to death at the moment. Is there anything I can do to calm him down? Or should I see if petsmart will let me exchange him?