Wildlife and Fish Ponds in Winter


Some really useful FAQ’s specifically focusing on fish and wildlife ponds in winter when the frost, ice and snow arrives

My pond was full of frogs and tadpoles over the spring and summer: where have they gone?

Frogs will generally hibernate in the lower levels of ponds, down amongst the leaf litter and plants. They are able to tolerate very low oxygen levels but can only survive a few days if the pond becomes completely de-oxygenated. The easiest thing to do, is to ensure that your pond plants are always getting some day/sun light and can continue to produce oxygen under the ice.

When your pond is covered in snow it will be totally dark under the ice which will stop the submerged plants and algae from photosynthesising and creating oxygen. Carefully sweep away as much of the snow as you can to allow the light to reach the plants.

Tadpoles can also occasionally overwinter in the water when they don’t develop fully during the summer and autumn. Very little is known about their survival chances overwinter: but it is likely that keeping the pond in generally good shape is the best thing you can do.

How will dragonflies, water beetles, mayflies and all the other invertebrates cope with the cold weather?

Most pond wildlife will generally be fine as long as the pond doesn’t become de-oygenated. Clearing the snow away is probably the easiest thing to do. Continuing to run your pump will certainly help fish, though no-one knows how it affects the rest of the pond’s wildlife.

Ultimately, good water quality, and allowing plenty of submerged plants to grow is probably the best way of making sure that your wildlife survives well overwinter.

I have goldfish, koi or other fish in my pond: how can I help them survive?

Pond owners traditionally oxygenate their ponds in winter to help the fish. This is because we often keep more fish in small ponds than can strictly be supported by the natural processes of oxygenation and water purification. This is fine as long as you can keep the pumps or fountains running, and is helped by the fact that in winter fish have very much lower oxygen needs than in the warmer weather.

Goldfish are amongst the most tolerant of freshwater creatures to lack of oxygen, and can survive at least as long as frogs completely without it. Be warned that this isn’t much more than a week or two, so under snow covered ice, even goldfish are at risk.

Koi require additional care as they are generally more delicate, they need more oxygen but even if there is a good oxygen supply they may simply be too stressed by the cold weather to survive – and fish once are weakened will often be killed by parasites and diseases after the cold weather eases.

It’s always worth trying to keep some circulation going. When icy, keep a bit of the ice open, run a fountain or waterfall/cascade, and make sure the pump continues to work.

Are newts safe from the cold weather?

All amphibians are as happy out of the water as in it during the cold weather as long as they can stay moist and safe from freezing temperatures.

A compost heap or log pile – where temperatures stay above zero, provides a perfect overwintering hideaway or hibernaculum for your amphibians. Damp or decomposing wood has a higher moisture levels and is favoured, above drier wood. Amphibians prefer to hibernate in small spaces, so packing in loose soil or wood chippings will make hibernacula more attractive. Sometimes they can hide under paving slabs, garden sheds or even the greenhouse, so make sure you are careful when doing any garden renovations in the winter. Newts can also occasionally overwinter in the pond too.

When icy, should I break it?

Making an opening in the ice can all creatures in both your pond and garden. It’s just possible that amphibians trapped under the ice of a de-oxygenated pond could be saved by being able to reach open water – and air. But as finding air holes probably isn’t part of their natural behaviour this may be more a kind thought on our part than a really good way of helping our animals. In fact, it’s more likely that amphibians would go looking for air holes at the very edge of the pond because this is where ice always melts first (because the land warms up more quickly than the water) – so if amphibians did go looking for oxygen, evolution would probably have pointed them towards the edge of the pond.

You can buy pond heaters and floating ice preventer’s which will in turn, keep the water temperature above freezing and maintain an air hole.

Alternatively an inexpensive cheap football floating on your water will always ensure you have a round air hole in the ice if the pond freezes over (quite often it pops out as it flexes against the ice gathering around the ball)

Is my pond going to freeze solid?

It’s unlikely that ponds, even shallow ones, will freeze solid. In this country it’s rarely cold enough for more than 2 or 3 inches of ice to form on our garden ponds, so only the very shallowest ponds, or small container ponds, can freeze completely solid. As long as your pond creatures have undergrowth to nestle in and a good oxygen supply they should be fine.

Safety around frozen ponds.

Take care around frozen ponds, they may look solid but you should not attempt to stand on them. Clearing snow will also help keep any children playing in your garden aware that the pond is there and help alleviate the risk of them falling through the ice.


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