This is my first winter with my small 5 X 5 X 3 deep pond & goldfish. I've cut way back on their feeding as the temps are dropping down into the low 20s at night. Anything I should know about their feed during cold months?

I'm also wondering if I need to leave the Pond Boss waterfall pump running continuously to help keep the water from freezing? I have an aerator pump & bubbling stone in there now & the waterfall 24/7.

As always, any tips & advice gratefully accepted. TIA.