Koi and other cold-water pond fish can typically go without eating for several weeks to a few months during the winter. This is because their metabolism slows down significantly as the water temperature drops, usually below 50°F (10°C). At this point, their digestive systems enter a semi-dormant state, and they stop actively feeding. Fish here in the Midwestern US typically go three months without eating. When water temperatures are below 50°F (10°C), these fish do not require food because their metabolism is too slow to digest it. If food is provided during this period, it may remain undigested and cause health issues or water quality problems. These fish tend to become less active in colder water, staying near the bottom of the pond where the temperature is slightly warmer. Monitor water temperatures and only resume feeding when the water consistently warms above 50°F (10°C) in spring. Always use easily digestible food, like Aquascape Premium Cold Water Fish Food Pellets during this transition period.