Even though your pond fish eat less during cooler weather, it's still important to maintain a balanced diet. TetraPond Spring & Fall Diet fish food helps koi, ornamental goldish and all other pond fish of any size to transition in and out of winter. Feed in spring and fall, when water temperatures are between 50 and 39 degrees. This transitional food is formulated with wheat germ, a highly digestible protein even at low water temperatures. Proper nourishment in the spring and fall helps support a healthy immune system in your fish.