Winterizing your pond will protect your water quality and the health of your fish and plants even through the cold of winter. Of course, some plants and fish are simply unsuited to freezing temperatures, and may need to be retired or moved inside until things warm up. However, hardier fish and plants can do just fine throughout the winter with just a bit of preparation. Most fish require a few feet of open water underneath the surface layer of ice, so make sure your pond is deep enough to provide that room. Fish enter a period of dormancy in the winter where their metabolism slows significantly as there is less access to food. Take temperature readings of your pond, and reduce the frequency of feedings once it drops to between 70 and 50 degrees. Once temperatures are below 50 degrees, you can stop feeding them entirely until things warm back up.
Keep a heater in your pond in order to provide a part of the surface where ice won't form. This will allow oxygen to pass into the water and for toxic gases, like sulfur, ammonia, and carbon dioxide, to escape. Organic matter and debris should be removed from your pond before winter starts. This reduces the amount of decomposition occuring in your pond once ice starts to form. Decaying organic matter releases gas into the water, and can have serious consequences for your water quality.
