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.

[4] The fish was introduced in the 1960s into ponds in Nucet, Dâmbovița County, Romania and it made its way into Danube, then spreading throughout Europe.

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.