Well over the weekend we went to petsmart and adopted a cat that the fish can tease. The cat, Mars, was from a local no kill cat rescue and has noticed the fish but has yet to figure out to get up to the tank. Nothing beside it to jump on and too tall to jump on top of from the floor. But I did hold him at tank level once and boy did the fish have fun swimming right by the cats face getting him all excited. My kids love Mars as well. He takes my one year old sitting almost on top of him and tugging gently at his fur. No hisses or biting or even trying to scratch her. I think this might be a good toy for the fish.