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Effects of Winter Weather on our Pond and Fish
September 08, 2009

Welcome from the Koi Pond Guide to all new subscribers.

As winter approaches in those climents that endure cold weather, we need to consider what is happening in our ponds as the water turns cold and the fish become less active and the exology of the pond changes.

Do you know how cold your pond water really gets? If you don't you should find out. You should know which temperature zone you live in and that will help you determine the expected frost line depth in your soil. On the outdoor pond page it has a Hardiness Zone chart (it is after the article on Inexpensive Dechlorinator). You could also ask your local agriculture extension services or your local garden shop. The importance of the frost line is that this is the depth that the soil temperature will potentially reach. The soil around your pond will act as a natural insulator and keep the water at the bottom of the pond at a temperature above 35 degrees F. The soil temperature at depths twice the frost line will not drop below 40 degrees or so, thus providing a nice natural insulator for our pond water.


The tropical water lilies pages are now up come and see the pictures of these beautiful plants. Blue Tropical Water Lillies


Water Temperature

For a pond where the filter system is not running or will be shutdown for the winter this next part is for you.

As the water temperature at mid-depth of the pond begins to drop and hold at lower readings, we need to pay special attention to what is happening to the ecology of our ponds. When your water temperature reaches 62 degrees F, the activity of the nitrosomonas bacteria begins to reduce primarily as the fish begin to slow down and produce less ammonia through respiration (less ammonia, less nitrogen processing). Also at 62 degrees your will see a significant dip in the Koi's immune system's ability to fight off bacterial invasions. This is where your fish can start becoming increasingly vulnerable to ulcer and other bacterial infections. If your fish are strong and the pond is healthy (well cleaned), the owner should not have problems.

Another water temperature mark to look for is 55 degrees F. At 55 degrees, the nitrifying bacteria in those ponds where the filters have been shut down will start to die off, they will be completely gone at 42 degrees F. While the fish are still producing ammonia primarily through respiration, we need to consider methods of reducing ammonia output. Here are some recommendations:

Change the diet of your fish to a food with lower protein content. The reason for doing this is, it is protein content in food that is a major contributor to ammonia production by the fish. By lowering the protein levels in the food, we thereby lower the ammonia output. Look for a food with a lower protein content, somewhere in the range of 30-32 percent.

Next,as the water temperatures drop into the 55-degree range, the Koi's metabolism begins to slow down and its need for nutrition reduces as well. This will allow you to reduce the amount of food provided to your fish.

For many years, Cheerios was recommended if the owner had to feed the fish something (guilt complex) and the reason for using Cheerios was it has zero amount of protein. But, Cheerios is high in carbohydrates, that makes it not good for fish in cold water conditions because they are unable to burn off the carbohydrates effectively. A lower protein fish food is a much better choice if you HAVE to feed them.

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Another thing to consider regarding feeding is that owners should NOT "pack it on" during the fall as teh fish's natural storage and processing systems provide for sufficient nutrition all winter long. Remember, Nature is their original "mothers" so Nature provided a way for them to survive during winter.

At 50 degrees F, stop feeding your fish altogether. At this point the fish's much lower metabolism will not allow proper processing of food in the gut. Koi, unlike most animals, do not have stomachs and so all food is process in the gut. With a slower metabolism, the food moves through the gut slower and the body's need for nutrients is reduces as well. If overfeeding during cold weather occurs, there is a real chance that the food will spoil in the gut and cause significant damage to the fish intestinal tract and quite possibly KILL your fish.

And finally, at 40 degrees F, all nitrobacter activity in the pond ceases if the filters are not running. If the owner plans on shutting down their filters for the winter, this is a good time to do it. When the you should shut down the pumps and filters is a call only you (the owner) can make, but the overriding concern is freezing of the plumbing and the loss of a pump, filter, or worse yet-the draining of the pond from a ruptured water line.

Reference: Richard E. Carlson

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Also, your comments are welcomed and appreciated!

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