The introduction of fish to fresh waters within a river catchment outside their natural range.
At least 11 non-native species currently have self-sustaining populations in NSW waterways. These include many species such as carp, goldfish, redfin, gambusia, banded grunter and oriental weatherloach that have been introduced for a range of reasons. Fish introduced to waters outside their natural range can impact on native flora and fauna in a number of ways including predation, competition for resources, habitat degradation and by the spread of diseases. Several threatened species are affected by this threatening process.