I have a heater and a waterfall and am have the worst time keeping a hole in
the ice. The ice is even freezing above the heater. We have had sub zero
weather in the day and wind chills up to 20 below.
I thought to cut a hole with whatever they use for ice fishing.
I have been able to push my heater in deeper by hitting it with a stick and
it frees it.
It is very imp to cut hole. I do not know how long fish can survive but I
don't think it will affect them for a short time.
My pond froze over completely 4about 4 years ago. My goldfish survived but
ALL my Koki died.