I think you want some depth in at least part of it even if you bring the fish inside in the winter. Shallow water gets hot, that can be bad for the fish. Since mine is a man made farm pond, generally speaking without any incoming water other than rain, it warms up and gets full of algae. It is nasty. Then, if we get lucky it cools down and rains a bunch and the algae dies off some. It would be better if there was a spring that fed it year round but that isn't the case. The spring only feeds it a bit in the spring time.Thanks. I hadn't thought of that. So bring inside in winter then maybe? I still prefer slightly deeper ponds though but idk. Not too deep I guess so I can see the fish.