I was trying to ask about the level of stress on fish coming out of winter.
Instead, I added extraneous examples which "muddied the waters". It is very hard to express "tone" over the internet!
To rephrase: Are there any small actions we can take coming out of winter that can have a significant benefit to the health of our fish?
As regards the pond temperature issues:
I agree that ice over the pond is a good insulating blanket when the air temperatures are lower than the water temperatures.
Then there is the point where you have 39F water at the bottom of the pond and 35F at the top. 37F air would heat the pond without aeration, but with aeration you might actually cool the pond.
P.S. Thanks for your suggestion to add some cold-adapted fish.
In southern Kansas, I have managed to miss the sweet spot for warm water fish AND miss the sweet spot for cold water fish.
However, both Teehjaeh and Snipe have been giving me a bunch of recommendations to at least attempt a deep, cold-adapted fish pond at our farm!
