How to Maintain Fish Over Winter in Outdoor Fish Ponds

Outdoor pond fish require very little attention during winter months because they are cold blooded, and their body temperature is regulated by their surroundings. When the pond water temperature drops, fish stop eating and go into a state of lowered metabolism and body function to survive cold-weather conditions. Pre-winter pond preparation and maintenance establishes a healthy environment for your fish, helping them through their dormant period and into spring when they start to eat and become active again.

Things You'll Need

  • Pond net
Show More

Instructions

  1. Preparation

    • 1

      Remove excess algae, debris and leaves from the pond water. Cut back old plants and trim leaves from overhanging branches around the pond.

    • 2

      Cover your pond with a net to prevent dead leaves from entering the water. Clear away collected leaves regularly so the net never becomes heavy and remains above the water level at all times. Leave the net in place all winter, and garden debris will not drift into the water, accumulate at the bottom of the pond and decay.

    • 3

      Check to be sure your pond filter and pump are working efficiently, and if necessary, remove algae build up from the impeller and protective cage. Do not clean your filter in anything other than pond water, because it must retain its live beneficial bacteria to maintain a stable environment for your fish and plants.

    Maintenance

    • 4

      Reduce the amount of food you give your fish at the end of summer, and change to a wheat germ-based fish food throughout fall months. Wheat germ is more digestible at lower temperatures and produces less waste in the water.

    • 5

      Reduce the water flow in your pump or switch it off completely. Algae is not prolific at low temperatures so you may also turn off UV filtration. Experts provide conflicting opinions as to the necessity of a filter and pond pump in the winter. It appears to be a matter of personal choice.

    • 6

      Remove uneaten food at the end of each day and stop feeding your fish when the water temperature drops to around 45 F.

    • 7

      Float a small ball or chunk of polystyrene on the water surface to allow gases to escape if the pond freezes over. This is not essential, but some pond keepers choose to do this as a safeguard if they switch off their pump and filter.

    • 8

      Monitor your fish for signs of disease, stress or ill health at regular intervals.