Question for my In-laws

They have a small pond in SE NC USA and it is built into a small hill that
they fabricated w/ dirt/sand mix and rocks on the outside of the hill. They
usually have the pump that sprays straight upward running but w/ the cold in
the AM the top of the pond freezes and the pump does not look like it is
working. They do have a special grass in it for the fish (around 20 small
ones) and they have turned off the pump for the winter. However, they are
still trying to feed them. I did not think that they were to feed them
during the winter??? Should they try to keep the top of the pond from
freezing?? IE Braking the ice in the AM everyday?? Any suggestions?? I am
not an aquariist (is there such a word??) So I am asking for any suggestions
that they should know about for now and the future.
TIA!!
cjack