How deep is the pond and where are you located? We need to know what your winter is like.

I live in southeast Wisconsin. The deepest part of the pond is around 16" inches.

Hopefully someone in your region will opine, but my guess woukd be the entire pond freezes so fish would not survive. Don’t worry about the frogs. They should know what to do. On my property they migrate to the larger pond whence they came, faithfully returning to the little pond in the spring.

What do you do with all the tadpoles? I have an above-ground 300 gallon stocktank and a 100 gall that I have to empty every Fall. I slowly collected all the tadpoles (hundreds) and put them in a nearby creek. I've never tried keeping a heater in an above ground small watergarden. But I've learned that after you drain it, you must turn it over. I didn't one year and the rainwater/snow in it froze and caused the stocktank to rupture. Just curious.....what kind of tank are you using?

All I have is a rigid plastic pond liner. I drain mine and then cover it so that the snow and rain doesn't get into it. It's easier than pulling it out and flipping it over I think. As for tadpoles I never saw any, I put the fish and an aquarium inside the house. Being that they're goldfish I didn't need to heat the water although I can if I want. All but one frog left on its own. So I released it in the garden near the compost heaps. I heard they like to burrow into them for the winter.

Sounds like a good plan Steven!