Oh skip the fish. Fish are only good for eating frog tadpole and eggs. Many amphibians won't even attempt to breed in ponds containing fish. If you want some frogs and toads, why not see what's native to the local area and try to collect eggs or tadpoles? Obviously, be sure you can do so legally - California is known for extreme laws that come in too late to be anything but a pain to enthusiasts (e.g. axolotls).