Controls on the Keeping or Release of Non-Native Fish in England and Wales

The introduction of non-native fish species can have far-reaching and undesirable ecological consequences for animal and plant communities in rivers and lakes.

Introduced non-native fish can have direct effects on native species, for example by predation, or can upset the natural ecological balance. Non-native fish can also introduce novel diseases and parasites to which our native populations may have no resistance. Zander and signal crayfish are good examples of non-native introductions that have already harmed our native fish stocks.