When the days become warmer and sunnier and new green shoots start to appear, we know that spring is upon us. But how are the fish in your pond doing? They will slowly be waking up from their winter dormancy and start to swim around more actively. They now need food as their digestive system is gradually kicking in again. However, the cold winter temperatures mean that their immune system is not particularly active and may even be weakened. We take a look at what kind of spring care you can do for your pond fish.

In the case of smaller garden ponds or those with low water depths, fish survive the winter best if you move them into your home or other frost-free environments. Certain goldfish species are definitely unable to cope with the winter temperatures and should always be moved indoors.

Once the pond’s water temperature has risen again (ideally to constant temperatures of over 10°C), you can finally return your fish to your pond. Before doing so, however, you should allow them to acclimatise to the water temperature. To do this, gradually add some of the pond water to the container you used for your fish over winter. This allows both the water temperature and the water parameters to gradually come into line. Your fish get used to the new conditions without any stress and can then be returned to the pond.

Did you leave your fish in your pond over winter? The point when they have become active again is a good time to check your fish stock as well as to get an idea of the maintenance measures you need to conduct in and around the pond in the near future. These can include plant care measures, checking the water quality and scheduling partial water changes. Don’t forget to also check the technical equipment (pond filter etc.) installed in the pond.

When the water temperature increases, the time has come to reactivate your pond filter. As you should have cleaned the filter before winter began, when spring comes around, all you need to do is check its electrical functions, then add the filter substrate and restart the filter. Please note, however, that biological filtration will not be instantly fully effective as the still cool temperatures mean that the filter bacteria need longer to settle on the substrate and become active.

Your fish’s good health primarily depends on the water quality. As such, you should regularly test the water parameters in your pond. In early spring, it is particularly important to regularly check the ammonia and nitrite levels as you will have started to feed your fish again and biological filtration only takes effect gradually.

You should also check the other key water parameters, such as the carbonate hardness and pH-value. If critical limits are reached, a major partial water change must be conducted as a matter of urgency.

Irrespective of any partial water changes you conduct due to poor water parameters, you should also conduct a larger one in spring at the latest. No matter how well you prepare your pond in autumn, the water quality will still always deteriorate over the winter months. Larger partial water changes are therefore not only an important pond care measure for spring but also the best way to kick off a new and successful pond year.

Pond fish are usually members of the large carp family. Many of them, especially koi, have a natural ‘problem’: their immune system stops working properly in low temperatures. As the fish also have to draw on their own resources to survive the winter, they will no longer be as fit and healthy by the end of this season. This makes them more susceptible to fish diseases when the water temperatures rise again in spring. Correct autumnal conditioning is therefore the best way to help your fish stay fit and healthy for spring.

Pond fish are particularly susceptible to disease in the early stages of the year. Parasitical and bacterial infections are especially common. You should therefore closely examine and monitor your fish so that you can respond to problems quickly, if necessary in line with professional advice. Warning signals include fish remaining apathetic after the water temperature has risen, fish with wounds or inflamed areas on their skin or fins, a grey coating on the mucous membranes and unnatural breathing.

You also need to take action quickly if you notice white spots or cotton-wool-like fungi formations on your fish. Specialist retailers can provide appropriate and effective medicines that are well tolerated by fish and should be used in line with their instructions. Please note, however, that even the very best of medicines cannot help your fish in the long run if they are not offered the best possible environment through the use of appropriate care measures.

Once temperatures increase and your fish become active again, you can start to feed them as their natural reserves will now be very low. If the water temperature is still below 10°C, you should feed your fish with special food. For example, wheatgerm products are easy to digest and particularly good for the fish as their metabolism is only starting up slowly. You should also start by only feeding your fish small amounts to ensure that no food residues remain in the pond. This kind of feeding in spring (and again in late autumn) helps your fish stay fit and healthy for the best possible start to the new pond year.