A Koi's metabolism functions best at temperatures above 70°F. High protein foods are difficult to digest when the water falls below 65°F. However, Koi still need sufficient carbohydrates for energy when water temperatures are low.

This is particularly true for Koi less than 1-year-old. Squash, bread, peas. citrus fruits and watermelon are good sources of carbohydrates. Koi do not have a stomach. Feed smaller quantities more frequently for better nutritional absorption. Feed only as much as the fish will eat in about 3 to 5 minutes. Koi pellets should be fresh and used within three months to prevent oxidation of the food.