The topmouth gudgeon (Pseudorasbora parva) is a highly invasive freshwater fish species in the UK, introduced through the ornamental fish trade. Native to Asia, it has established populations in various water bodies and poses significant ecological threats. This small fish competes with native species for resources, preys on their eggs, and can spread diseases and parasites. Its rapid reproduction and adaptability make it a major concern for aquatic biodiversity in the UK.
