Winter is a transitional time for a pond. From fish and food, to equipment and plants, caring for the pond in the winter is an important time for your ecosystem.
Fish and Food
In most parts of the United States fish can be left in the pond during the winter, providing the depth of the pond is adequate (18 inches minimum or deeper in harsher climate zones). Fish will gather in this deepest area of the pond where the water temperature remains more stable and go into a state of hibernation during the winter months. Note that some types of fish, such as plecostomus (sucker fish/algae eaters), fancy goldfish with ornate tails, bubble eyes and lionheads, are sensitive to cold weather and should be brought indoors. Here at Cool Ponds, we leave our koi and goldfish in our ponds.
As winter approaches, you should monitor pond water temperatures daily. When your water temperature is between 70°F – 50°F, you should feed a cool weather fish food (available at Cool Ponds). Once the water temperature falls below 50°F, you should stop feeding the fish altogether. Some may worry about not feeding their fish, but you can rest assured that your fish will naturally rely on stored energy reserves built up during the summer to sustain them throughout the winter months. Cool Ponds sells pond thermometers perfect for monitoring your water temps.
In the past, readers have asked us for advice on what to do if they are NOT closing up the pond because they live in a warmer climate. If you live in a spring or summer-like region, like we do at Cool Ponds, we suggest you continue to monitor your temperatures and follow our Cool Ponds Seasonal Feeding Cycle. If you have premium Koi, continue to feed Blackwater Creek Cool Season Koi Food. Blackwater Cool Season food is blended to be easily digested during the seasons when water temperatures stay below 60°F (16°C). During this time of year your fish’s metabolism slows and digestion is more difficult. The Cool Season diet contains a complete mix of ingredients for the cooler times of the year. Feed this diet prior to breeding season to reduce fat deposits and the possibility of “egg-bound” females.
If you live in a cold climate, disconnect the pump, filter and UV clarifier before water freezes. Be sure to store the UV clarifier indoors for protection. It is also a good idea to store filters indoors (if manufacturer’s directions suggest). If you live in a northern climate zone where your pond will freeze over, it is very important to purchase or have a pond de-icer ready for installation. Gases, which are produced by decomposing organic material, are toxic to fish when they are trapped beneath ice covering the pond’s surface. Only a small hole is needed to allow these gases to escape and ensure the survival of your fish.
Most aquatic plants (with the exception of tropical lilies, water lettuce and water hyacinths) can be left in the pond through the winter. Trim back all dead foliage, and then submerge the plants in the bottom or deeper section of the pond to prevent the plants from freezing. Hardy water garden plants will come back year after year. Consider bringing tropical lilies, water lettuce and water hyacinths indoors for the colder months.