The stone moroko (Pseudorasbora parva), also known as the topmouth gudgeon,[1] is a fish belonging to the Cyprinidae family, native to Asia, but introduced and now considered an invasive species in Europe and North America.

[3] This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.

Four phylogenetic lineages of Pesudorasbora parva were identified within its native range, and three of them contributed to the dispersal within more western regions of Eurasia.

[7][9] A 2023 study showed co-introduction of three monogenean species, Dactylogyrus squameus, Bivaginogyrus obscurus, and Gyrodactylus pseudorasborae into Europe along with their fish host from East Asia.

Monogenean infections were generally lower in non-native host fish, potentially giving an advantage to this invading species.