Hi
I had one but it was with tropicals and was always trying to catch them. If you really want one put it in a tropical tank with top and mid swimming fish. Goldies may be too slow and get their fins caught by the claws.
I was going to say maybe use bands to tie the claws but can it still eat?
I have heard that people take the claws off them, but i think thats cruel and unneccesary.