Topmouth gudgeon Pseudorasbora parva: a side effect of fish stocking

he topmouth gudgeon Pseudorasbora parva is an eastern-Asian cyprinid species, which inrelatively short time has colonised nearly the whole Europe. In some regions it has become a notablereproduction success and significantly disrupted native ecosystems. Such a fast expansion is mostprobably caused by uncontrolled transfers of stocking fish, mainly Asian carps, i.e., Ctenopharyngodonidella, and Hypophthalmichthys spp. The case of P. parva invasion demonstrates the risk oftranslocations of fish, as well as urgent need of more caution and prevention in order to avoid furthersuch unexpected guests.