What are tadpole's predators?

This depends on the type of tadpole. Frog tadpoles are particularly subject to predation by fish, birds, lizards and even other amphibians. Toad tadpoles, on the other hand, have been shown to be rather unpalatable, and less likely to be eaten by those creatures listed, but are just as likely to be preyed upon by creatures with sucking mouth parts rather than chewing mouth parts.