Fish care about food. I used to keep an Oscar, and had a smaller tank with feeder fish as a weekly treat. If i showed Oscar the little net he would immediately swim close by the net, then follow it down to the bottom of the tank, then back up with the snack Tilapia. Only 2 were faster than him, and lived in the tank for a few years with him until they got too big, when I returned them to the dam.