Pond fish do not require food during the winter months because they are cold-blooded creatures. Their metabolism and body functions slow down as the water temperature drops, until the fish reach a point where they are able to exist in a state of near-hibernation to survive extremely cold conditions. When the pond water temperature starts to rise in the spring, the fish become active and regain the ability to eat and digest protein efficiently. Wait until the water temperature rises to an appropriate level before you reintroduce food to your pond, and do not overfeed your fish.
Check the water temperature when your pond fish start to come to the surface and look for food. It is important you do not feed your fish until the water is at least 14.4 to 15.6 degrees Celsius. If the water is too cold, fish are unable to complete their digestive process and excrete the undigested food into the water as harmful waste, providing a breeding ground for bacteria.
Choose a wheatgerm-based fish food with around 20 per cent protein content and feed your fish according to the manufacturer's instructions. Wheatgerm fish food is designed to produce minimum waste at lower temperatures, and your general pond health will benefit from reduced waste production.
Acclimate your fish back to their regular feeding regime. Feed your fish early in the morning to allow plenty of time for digestion, and when the daily water temperature is consistently above 15.6 degrees Celsius, reintroduce staple summer food.
Test the water every other day after you start feeding your fish. Ammonia, nitrate and nitrite levels drop to zero in extremely low temperatures when there is no food waste in the water. When you resume feeding your fish in the spring, warm water and fish waste quickly combine to kick start the nitrogen cycle and ammonia levels can rise to a dangerous level, even in an established pond.
Pick out leaves and other debris that have accumulated over the winter, and carry out general pond maintenance to ensure a healthy environment for your fish before the summer months.
Do not feed your fish too early in spring. They may appear to be looking for food but if the pond water remains cold all day, algae and plant matter is all your fish are able to digest until their body temperature rises naturally with the weather.
A fish's immune system does not reactivate until the water temperature reaches 14.4 degrees Celsius, so do not allow waste from undigested food to remain in your pond during cold weather because the bacteria will harm your fish.