Rubber Duckie you're so fun

Telima,
I have a possible solution to your problem. I only hope it works. Take some Clorox, not full strength but mixed abut half and half with water. After the bath, take the ducks and squeeze out all the water you can and then fill them from a bowl of the Clorox water and then squeeze them out again. Do this two or three times and then rinse them with just plain water a time or two, It will at the least kill any mold. You may have to do it every few baths. If it doesn't work then the only other solution is to throw them out and buy new ones.