What happens with my fish in the winter?

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Leave them in the pond. If you have cold water tolerant fish (e.g. Koi) and your pond was designed and installed correctly, they will be just fine under the ice until it thaws in the spring.  Now, you can’t just forget about them completely.  You will need to do a couple of things to ensure their health and survival.  First of all, do not feed them when the water temperature drops below 50 degrees F.  The food they eat can sit in their digestive system, begin to rot, and be very harmful to them.

Pond, Waterfall, Koi, Water Lilies
Later Summer Pond.  Koi looking for food.

As the temperature continues to drop and before the ice forms, remove as many leaves and other organic matter as you can (e.g. other plant material and sticks), and install a bubbling pump and deicer / pond heater.  These are added to ensure that an opening remains in the ice at all times.  Why is this important?  Your fish will continue to produce waste (e.g. ammonia), and we need to get that out of the water.  They also require dissolved oxygen which they consume, along with remaining organic matter in the pond that is decomposing.  The opening in the ice is critical to the gas exchange of the ammonia leaving and the oxygen entering.

When installing the winter bubbling pump, be sure to not place it on the bottom of the pond.  When the ice forms over the pond, the water that is at the bottom of the pond is the warmest and this is where the fish will hang out.

During the winter, be sure to check on the openings in the ice, especially after a snow storm or a lot of wind with blowing and drifting snow.  If the opening becomes covered with snow, be sure to remove the snow by lightly shoveling it away.
The pond just after the storm.  Deicer and pump need to be uncovered.

Your fish greatly appreciate the attention you give to them, and you will get to enjoy their company again in the spring.

Visit our website www.AquaticInnovators.comfor more information and be sure to share your winter experiences with pond fish or contact us with any questions. We can be reached by email at Shawn@AquaticInnovators.com or by phone at (608) 373-7040.  Have a great day!