How to Look After your Fish in Winter

As the cold weather draws in, the welfare of your fish may become a concern. With temperatures going into the minus figures and ice forming on the surface of the pond, you may be concerned about your fish. We find that new pond owners inquire about what to do with the pond in winter; if the pond does not freeze over, your fish will be fine.

During the winter period when the pond temperature goes below 10 degrees Celsius, your fish will enter their period of hibernation. Essentially, their metabolism drops, and they rest at the bottom of the pond. This means your fish will require less care and you won’t need to feed them throughout this period.

How to prevent your pond’s surface from freezing over

It is easy. There are several methods which can prevent a pond from freezing over. The main priority is to ensure that there is a gap in the ice; this allows harmful gases to escape the pond. If these gases build up under the ice, this will pollute the water and will endanger your fish. Maintaining a hole in the ice also allows pond life access to the water should they need to.

• Keep your Pump running – This forces the water to circulate and prevents it from freezing over. But try to keep the pump away from fish and below the ice levels of your pond. You do not need to filter your water as waste is at a minimum during winter.
• Keep an aerator turned on – Having an aerator running throughout winter will achieve the same as your pump; the air displaces water and forces it to move, preventing the surface from icing over. We actually recommend an aerator as one of our 5 Tips Which Can Make A Big Difference To Your Pond. On the benefits of aeration, please see our blog posts.
• Get a De-Icer – These are often small, floating heaters which keep the water hot enough to prevent the water from freezing over. They have very little affect on the temperature of the water, but they do affect a very small area around it. This stops the ice from forming.

The main aim of the above methods is to prevent ice from forming on the surface of the pond. This is highly important. But they can also help to aerate the pond, which is extremely beneficial to fish health and sludge management. The extra aeration will help to improve healthy bacteria in the pond, which in turn improves decomposition of debris to prevent a build up of harsh chemicals. So it is really important that the water is properly aerated; either through a pump or an aerator.

What do I do if the pond has already frozen over?

If your pond has frozen over, you will need to act quickly to resolve it. In short, you will need to remove any snow or surface debris off the ice and then try to melt the ice using a pan filled with boiling water. Avoid using a hammer to break the ice, as this can send shockwaves through the pond and disturb your fish while they are hiberating. More information on this can be viewed on our What To Do If Your Pond Freezes Over.

Do I need a Pond Heater?

As above, pond heaters work by gently warming the area around the heater to prevent ice from freezing. This allows the gases to exchange in the pond and pond life access. More importantly, pond heaters are a simple way of maintaining your pond through winter and they are often cheaper to run than keeping your pump running!

Do I feed the fish in Winter?

As briefly outlined at the top of this blog post, you do not normally need to feed your fish throughout the winter once the pond water drops below 10 degrees Celsius. Further information on this can be viewed in our blog post Fish Food: When to Feed your Fish and What Food to Use. In short, there are two reasons why you should avoid feeding your fish while they are hibernating. Firstly, their digestion system slows down and they can't handle ther food. Secondly, any left over food will sink to the bottom and decompose; this can release harmful chemicals like Ammonia (which then affects your Nitrate and Nitrite levels).

Do I need to do anything else to take care of the pond?

The only other precaution you should take with your pond is to add a cover net. These will actively prevent debris from entering the pond; this is an important step as debris can form sludge and this can then pollute the water with harmful chemicals. A cover net will prevent this from happening.

You can find more information on Winter Pond Care using the below blog posts:
Pond Calendar
Pond Checklists
Pond Problems
Top Tips

If you have any queries, please email our friendly team on info@pondkeeper.co.uk.