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It’s getting to be yard cleanup time of the year, and that also means it’s time for fall pond maintenance. If this is your first year with fish in your pond, you might be wondering if they can stay in the pond or if they need to come inside for the winter. 

The good news: most pond fish can stay in the pond through an Illinois winter.  

The less good news: it takes a bit of maintenance to set them up for a safe winter.




Koi fish and most generic goldfish will survive through the winter just fine in a pond. More exotic types of goldfish may not survive winter temperatures, so check with your fish supplier about the specific varieties you have if you’re not sure. 

It’s important for your fish and your pond to be healthy heading into the winter. There are a few essential tasks to get both the pond and fish ready for winter. You can do all your spring and fall pond maintenance yourself. But, it can be quite a bit of work. 

If you don’t feel up to tackling spring and fall water feature maintenance, or you just don’t have the time to get it done, you can book a time for our landscaping teams to come out and take care of that annual maintenance for you. Then you can relax and know that your fish and your pond will be safe through the winter.



Essential Fall Fish Pond Maintenance  

If you do want to do some or all of your fall pond maintenance yourself, here are the things you need to do: 

  1. Clean your pond, trim back any water plants, and install a pond cover net to catch debris.
  2. Test the water and make sure the ph, ammonia, nitrate, and nitrite levels are safe. Check with your fish supplier to verify what is safe for your fish. 
  3. Remove and clean pumps, circulators, bubblers, and filters, and store them indoors. 
  4. Install a de-icer to keep an area of water open. 
  5. Stop feeding your fish when the water temperature hits 50º. 

If cold water from the surface is circulating down to the bottom, it may turn your fish into fish-cicles. 

The main concerns for overwintering fish in your pond are making sure there is plenty of oxygen in the water and that the pond is deep enough not to freeze solid. The recommended average depth for overwintering fish is a 36-48″ deep. 



Why You Need a Pond De-Icer

Your pond will need a de-icer for the winter to keep one area of water ice-free. If the pond freezes over completely, gases from decaying matter will get stuck under the ice, and oxygen will not get to the water. A de-icer allows those gases to escape and allows the water to continuously absorb oxygen. 

The birds that are around for the winter will probably also appreciate the de-icer in your pond.


Why You Shouldn’t Run a Pump or Filter in Winter

Don’t run a filter or pump. Water turnover means that the warmest water usually about 40º sinks to the bottom of the pond for the winter. This is where your fish will hang out, in torpor. If cold water from the surface is circulating down to the bottom, it may turn your fish into fish-cicles. 



Don’t Feed Your Fish in Winter

Torpor is a state of dormancy, sort of like hibernation. A fish’s metabolism slows down, they don’t need to eat, and they don’t move very much. Once the water temperature drops to 50º, you should stop feeding your fish. Don’t be tempted to feed your fish on those warmer winter days where the water temperature comes up above 50º.

Don’t wait too long to get your pond maintenance done, as it’s much easier to do before things start to freeze up or there’s snow on the ground. Once you’ve done your pond maintenance, keep an eye on it until it starts to freeze over. It’s best to clean up any fallen leaves off the surface frequently, so they don’t decay in the water. 


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And don’t forget, if you don’t have the time to get to your pond maintenance, just give our landscaping team a call. We can get it done for you, so you know that your fish will be happy next spring, and all your pond systems will be in perfect condition to start running again. 


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