Preparing Your Pond for Winter
Should you stop feeding your fish during winter?  For those of you who have “winter”, where the water temperature stays below 50° F, then yes.  If you have a mild winter with water temps above 50° F, then no, not really.
For colder areas, if you have fish in your pond, you can stop feeding them once the water temperature stays below 50° F. At this temperature fish will go into hibernation and stop eating. Set up a good thermometer to monitor the water temperature.
Rather than going cold turkey, wean your fish off food as the temperatures go down. When the water temperature is steadily between 55-60° F, only feed the fish once a day. Reduce feeding to once a week when the water temperatures stay between 50-55° F. If the temperature stays below 50° F, you can stop feeding them until the weather warms in spring. Discard any remaining fish food since the nutrients in any open packages will dissipate over time. If your area experiences a warm spell the fish can eat algae from the pond sides; you don’t need to feed them.
Finally, consider installing a floating de-icer to keep your pond surface clear of ice. In colder climate zones an air hole needs to be kept open to allow for a proper oxygen/carbon dioxide gas exchange for fish to survive the winter. If your pond completely freezes, you risk losing your fish.