It's hard to believe how fast summer goes by. You're no sooner sitting by a well-tended garden pond than the first leaf drops into the water - and that's when it’s time to winter-proof your pond. The animal experts at speciality chain Fressnapf are here to tell you what your scaly pond-dwellers need for their winter quarters.

If your pond is at least 80cm deep, the water will naturally form layers at winter temperatures, creating different temperature zones. Animals can hibernate right at the very bottom, where the temperature is around 4 degrees centigrade, so it’s important that these layers aren’t destroyed by outside influences. Only starting to clean your pond during the winter months or keeping the water circulating by using a pond pump can disturb these layers, so you should switch off your pond or stream pumps if the temperature drops to below twelve degrees centigrade. Otherwise there is a risk that the pond will freeze right to the bottom!

Along with temperature, oxygen content is crucial for the survival of your pond fish and this matters most when a layer of ice has formed. The oxygen content of the water under the layer of ice decreases day by day, which can cause breathing difficulties in the animals. There’s another problem too - if there is too much organic matter at the bottom of the pond, such as leaves, mud or dead plant matter, decomposition processes start up. Not only does this sap oxygen reserves, it also releases poisonous gases such as hydrogen sulphide or methane. If these gases cannot escape because of the closed covering of ice, all of the animals in the pond are at risk of death.

Here’s the solutionThe right time to remove loose or dead plant matter from your pond is right now, in the autumn. If the winter frost then causes a layer of ice to form make sure that there is always an ice-free air hole, for example, by using an air-stone or a plastic or polystyrene de-icer with a pump. You should never smash a hole in the ice, because the noise and force really upsets the fish and can cause high pressure in the water's lower layers. Alternatively you can also place bubble wrap on the surface of the water, with the pimples facing down. It acts as a layer of insulation against the cold and keeps ice and snow off. It may also allow any poisonous gases that have formed to escape.

Spending the winter outside the pond
If your pond is too shallow or if your fish obviously don’t cope well with the cold, it’s better if you can keep them somewhere else. It doesn’t have to be an aquarium. A large container, like a rain barrel or mortar trough, would also be suitable. Fill it half with pond water and half with fresh water. You should also install a pump or filter and ideally move the fish when the temperature is between twelve and seven degrees centigrade. If the temperature later drops to four degrees, it’s easy to transfer the fish into a basement or garage.


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Winter survival A de-icer will make sure that the water in your garden pond doesn‘t freeze over completely when it’s frosty. Photo: Fressnapf/Ulrike Schanz (Photos may only be reproduced with permission and in connection with editorial text. High-resolution photos can be requested from the Fressnapf press office.)