I was going to write a long answer but i remembered that there already was a good explanation at the link bellow.

an important quote from which reads..

" their entire metabolism slows to a crawl when the ambient temperature drops into the low 50s. Fish need very little energy (calories) at that point. "

simply put they don't forage, so don't worry.

It is important to note that at certain temps it actually becomes dangerous to feed them.

Here is a link that might be useful: Winter Feeding

I had read that article and I am going to get a thermometer to see what the water temp is. We have some really warm days in the winter and I see them nibble around on the algae and anacharis so I didn't want to starve them. I have always not fed them after October even when they beg but there was always natural food they could munch on if they wanted to.

Next year I will try to grow some anacharis in a separate tub. I am attached and can identify each one and don't want to loose any. What I would really love to do is build a green house around the pond for winter so I could go out and visit them after a hard day at work.

Would it put your mind at ease to know that there are ponders who never feed their goldfish at all? Not winter, summer, spring or fall. The fish thrive on the things that live naturally in the pond - algae, small bugs and microscopic organisms, etc. They also find it keeps the fish population down as they will eat any eggs that are produced as well. I've seen these ponds and their fish are healthy and happy. And fish do require less food in cooler/cold weather as their metabolism slows to a crawl. Too bad it doesn't work the same for us humans!