Fish and their immune system
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.