Fish can certainly die during winter, but not due to the cold itself. Rather, the cold can produce conditions that are unfavorable to fish survival. Luckily, there are a few steps a pond owner can take in order to ensure his/her fish will stay safe and healthy when the mercury drops.
One reason cold weather can endanger your pond fish is simple: ice.
If the surface of your pond is covered in a sheet of ice, then the exchange of gases is inhibited and can build up in the water. This is not good for fish as they can be starved for oxygen as more carbon dioxide and other gases build up under the ice. We recommend that pond owners keep a hole in the ice to allow for the proper exchange of gases. There are a few different ways this can be done.
First and foremost: your pond should be at least 2 feet deep.
This will give enough distance between the earth’s surface and surface of your pond so that it will only freeze to a depth of about 8″. As the water gets colder, however, you will notice your fish becoming much less active.
Another common misconception is that the pond’s pump should be turned off for the winter.
The running water created by your pump will help prevent ice from forming on the surface. If you do decide to shut down your pond for the summer, make sure to take the proper steps to care for your pump. For more information on this, check out this article for “Winter Pump Care.” If you’re like the majority of pond owners, you will keep your pump running year round. Even with the pump running, ice can still form on the surface of your pond and harmful gases can build up. There are additional things you can do to help prevent this dangerous build-up of gases. A pond aerator like Aquascape, Inc.’s Pond Air 4 is great for oxygenating the water. The bubbles from the aerator also help prevent ice from building up on the pond’s surface as well. If you still have ice forming after these steps, we recommend a pond a Pond De-Icer. It’s is a heater that floats on the surface and keeps a small hole in the ice to allow gases to escape. It is also important to clean as much plant debris (e.g. leaves) out of your pond. As leaves and other things decompose, they release gases that are toxic to fish. You can install protective netting over the surface of your pond to help keep leaves out of your pond. One way of creating a hole in the ice that we DO NOT recommend is using a saw or hammer to make a hole in the ice. Fish are particularly vulnerable in the winter and the vibrations created by sawing or hammering the ice can cause stress for the fish and endanger their health.
Contact our Graham, NC, store using the contact form on this page if you have any other questions about fall and winter fish and pond care and we will happily assist you! We service the central North Carolina area from Raleigh to Greensboro.
“Keeping Pond Fish Safe in the Winter” – deckandpatio.com
“What Do I Do with My Koi and Pond Fish Over the Winter?” – aquascapeinc.com