1. If the pond stays frozen too long, all the fish will die so getting
a hole in the ice is imperative! A pot of boiling water set on top of
the ice should thaw a hole if you haven't waited to long. Remember it's
the gases held under the ice that kill the fish, not the cold.
2. I use a livestock heater designed to keep water troughs from
freezing. Works beautifully. It's awesome to go out in the middle of
the winter and see the fish swimming about....especially when the snow
is piled high around the pond...