Kudos to you for allowing fish, but this is a bit silly. AFAIK the radiation dose from the x-ray machines is extremely low: lower than from medical x-rays, perhaps even lower than from a long flight.

I laugh whenever I read "horror stories" about people who send babies through the x-ray scanner (if that's abuse or neglect, then radiologists are horrible child abusers.) It would not surprise me if it was safer to put a baby through the x-ray scanner than to take the risk of dropping the child when going through the WTMD.