This is just.... disturbing. I don't think kids 7+ would harm their fish because of this, but younger kids might, and they are the ones that would want it more. Plus, it takes away from the fish. If you want a fish, get a fish. If you want a teddy bear, get a teddy bear. Not both wrapped into one. I can just picture this conversation:
Timmy: Mommy can I sleep with Mr Fishy and Mr Bear tonight?
Mom: No Billy, you cannot.
The multiple responses of Timmy:
Sleeps with it anyways.
Gets mad and throws it on the ground.
Takes the bear off the tank, and the tank spills.