A Koi's metabolism functions best at temperatures above 70º F. High
protein foods are difficult to digest when the water falls below 65º 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.