Wriggling Fish
This didn't turn out well. After switching it on (the switch is quite small), the fish keeps flapping until the battery runs out or I turn it off, even if the cat isn't playing with it. I used to have a fish that only started flapping when touched—if the cat ignored it, it wouldn't turn on. This one is also rather noisy. What a shame. I won't buy it again, it actually scares the cat more than anything.