Overwintering Pond Fish
Brett Fogle
The metabolism of koi and goldfish is controlled primarily by
water temperature. As the water cools, pond fish require less
protein in their diet. When koi and goldfish are fed high-protein
food in cool water, the excess protein is excreted as ammonia
from the gills. The microscopic organisms that make up the
biological filter (and consume ammonia) also slow down in cooler
water.
Improper seasonal feeding can lead to a build-up of toxic
ammonia, which stresses fish and reduces their winter
survivability. When the water temperature drops to approximately
65° F, start feeding with Spring & Autumn Pond Food. This type of
fish food is better suited for the dietary requirements of pond
fish in cool water and won’t pollute the water with excess
ammonia. Some water gardeners continue to feed their fish until
they no longer come to the surface. I stop feeding my pond fish
when the water falls below 42° F.
There is no need to worry about "frozen fish" if a section of the
pond is at least 18 inches deep. Pond fish will seek the deepest
part of the pond and over-winter there until the water warms in
the spring. If your pond is less than 18 inches deep, the fish
may freeze during a harsh winter. Check with your local pond
supplier if you live in an area with harsh winters.
Some water gardeners with shallow ponds attempt to keep their koi
and goldfish in kiddie pools or aquariums set up in a cool
basement or garage. This is not recommended because of the extra
stress involved in netting, transporting, and re-acclimating the
fish to the new environment.
However, if you don't have a choice, and need to bring your fish
inside for the winter, be sure to have an aquarium air pump or
small fountain to provide oxygenation. The fish should be fed
infrequently, if at all, depending on the water temperature. pH,
ammonia and nitrite, which should be monitored weekly and
especially if the fish are fed.
Small water changes (20%) each month will keep the water in good
shape until spring. Koi are "jumpers"-so be sure to cover the
pool with bird netting!
Brett Fogle is the owner of MacArthur Water Gardens and several
pond-related websites including
www.macarthurwatergardens.com and
pond-filters-online.com. He also publishes a free monthly
newsletter called Pond Stuff! with a reader circulation of over
6,000 pond owners. To sign up for the free newsletter and receive
a complimentary 'New Pond Owners Guide' for joining, just visit
MacArthur Water Gardens
