Stone moroko Pseudorasbora parva, is a fish belonging to the Cyprinid family, native to Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

, but introduced and now considered an invasive species

Invasive species

"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

 in Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

. The fish's size is rarely above 8cm and usually 2 to 7.5cm long.

Invasive species

The fish was introduced in the 1960s into ponds in Nucet

Nucet

Nucet is a town in Bihor County, western Transylvania, Romania. Its name means "walnut trees" both in Romanian and Hungarian. It administers two villages, Băiţa and Băiţa-Plai.-Population:...

, Dâmboviţa County

Dâmbovita County

Dâmbovița ; also spelt Dîmbovița is a county of Romania, in Muntenia, with the capital city at Târgoviște.-Demographics:In 2002, it had a population of 541,763 and the population density was 134/km²...

, Romania

Romania

Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...

 and it made its way into Danube

Danube

The Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....

, then spreading throughout Europe. They pose danger to another species such as the sunbleaks (Leucaspius delineatus), as they are the carrier of a parasite (Sphaerothecum destruens

Sphaerothecum destruens

Sphaerothecum destruens is a parasite of fish. It was first discovered in the United States in association with invasive species including topmouth gudgeon but was found to be the causative agent of a disease in the UK affecting salmonid species such as Atlantic salmon and brown trout...

) which while not damaging to the topmouth gudgeon, attacks other fishes like the sunbleaks, which are unable to spawn and have a higher mortality when infected.