Hi Roy,
Thanks for the compliments, and I hope to bring you all even better things in the future.
I don't think you'll have problems with tadpoles eating fry, but the adult frogs most certainly can. American bullfrogs were introuduced in Niigata at the end of the second world war as a food source, and are the scourge of koi breeders there. Are your frogs big or small? You should be vigilant against these frogs, and stop them from ever reaching adulthood.
If you have problems with big bullfrogs, you should inspect the edges of your mud ponds and grassy areas searching for the gelatinous eggs. Upon finding any, a generous dousing with caustic lime should disintegrate the eggs and help to keep your frog problem from getting out of control. If you have a copy of issue #1 of Koi-Bito, you will see Kataoka-san doing just that.
Not sure what you can do once the frogs have hatched and become tadpoles, except remove them at culling. I always see lots of smaller frogs in mud ponds in the southern areas of Japan, but they don't pose any threat except competing with the fry for food resources.
Brett, Brady, Maurice...any of you gents want to share your frog deterring strategies with Roy?
