Frozen fish

It's very cold here at the moment - the temperature's been below freezing for several days. Look at the state of our fishpond! It's only the pump which keeps it from completely freezing over. I am amazed that the fish appear to be OK - I can see them moving about below the ice. But they seem to have completely given up eating the fish food I occasionally throw at them. I'm fully expecting the entire pond to freeze solid before the end of the winter, in which case I suppose the fish will freeze with it...