Feeding the Fish. The short answer to this is: Forget It, even if the
fish look interested. In colder water, fishes' digestive systems are
sluggish. The best option for the hobbyist is to feed easily digested
foods, especially those made from wheat germ, when the pond temperature
drops below 55o F.. Feeding should be stopped altogether when the pond
temperature drops below 45o F.. Wheat germ foods should be again
utilized in the Spring, when the water temperature is between 45o F.
and 55o F., to provide an easily digested diet after the long cold
winter.