They most likely have hatched into tadpoles. It just takes a few days for this to happen. The tadpoles usually hang around where they hatch for another day or two, but are very hard to see. Your fish may eat the tadpoles. Tadpoles are one of the best natural algae controls you can get. Of course when they morph no more algae control, lol.

If you have Koi they most likely ate them. In 7 years I have never had a baby anything in my pond. Sorry.