Andy41 said:
Hi Guys,
I'm in the process of designing and building a new pond.
I'd like to stock Koi, but i'm a bit concerned about the winters we have here. Temperatures can be as low as -20C (-4F) but average -10C (14F) for most of the winter. The pond normally freezes solid from dec to feb with about 4 inches of ice.
I have goldfish at the moment and they survive this fine, but i've got no idea if the koi can cope as well..... ?
cheers,
Andy.
If you live in a place where the winters are mild with an occasional light snowfall it will be much easier and take far fewer steps to transition to a Koi winter pond. If you live in a place where the winters are intense and long, then there are a few additional details you will have to consider.
One of the first things you have to take note of is that plants and animals in nature handle winter by slowing down. Plants generally go dormant, some animals hibernate and your Koi, providing your pond is deep enough, hang out at the bottom where the water is warmer. There is a slow breaking down of the accumulated leaves, algae, fish waste and insects which have collected over the summer and this decomposition occurs because of the presence oxygen. Decomposition results in hydrogen sulfide, which is a toxic gas. Remember also, that the more waste that you neglect removing from your pond, the more there will be to decompose and less oxygen will be available to the Koi. With this awareness, you should prepare your Koi pond for winter by clearing up all the things that can lead to excessive hydrogen sulfide. Thoroughly clean your pond, removing all the dead leaves and other debris from the bottom. You can use a fine net and/or vacuum created specifically for this purpose. You can then use a net to cover it and make sure that no further leaves fall into the pond. It is also a good idea to change about 50% of the water as part of your winterizing process. This will be a good way of making sure that you are not going into winter with a dirty pond. After providing a clean setting for your Koi, you can now focus on the needs of the fish during winter.
The metabolism of Koi, like that of the goldfish, is controlled by water temperature. So, they reflect the falling water temperature with a corresponding slow-down of their metabolism. This means that they need less food, and specifically, less protein. Start monitoring water temperature carefully from mid-fall. When it drops to between 64-68 degrees Fahrenheit you have to start making changes in the diet of your Koi. Wheat germ based food is recommended as being easier to digest as it is lower in protein. As the water temps drop and the metabolism of your Koi slows down their bodies are less able to digest protein. When water temps drop below 50 degrees you need to stop feeding your Koi altogether Even if your pond doesn't freeze in the winter it is recommended that you cut back on the quantity of feed you use. Some say Koi consume only about 20% of their summer amount during the winter. Again, the type and amount of food will vary with the water temperature. Others use the fish as an indicator of how much to feed and only offer food when they come to the surface looking for it. Dropping feed which the fish may ignore and leave uneaten can affect the water quality negatively. It is also advisable to use a heater and/or de-icer so that the water does not freeze over completely. This will trap toxic gases under the ice and not allow for adequate oxygen to enter the pond. Keeping the water in your pond circulating with an air pump is also a good way to keep the pond from freezing over.
Those who live in harsher winter conditions have to assess the size of their Koi pond. If yours is a deep pond, ideally 3 to 5 feet in depth, your Koi will be able to survive the winter with a minimum of help and care from you. The deeper the pond, the more warm water space they will have at the bottom to wait out the cold weather. On the other hand, if you already have a pond and it is more shallow (i.e. less than three feet deep), you may have to bring your fish in for the winter. You can put the Koi in a small aquarium or a kid-sized splash pool, in your garage or basement, and follow the over-all winter-care pattern described above.
Remember that cleanliness, diet and water-circulation are three of the basic details for you to focus on while preparing for your Koi winter pond.
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have a heater in the water c) left them on their own and did ok