Fluvial fresh water blenny (Salaria fluviatilis), a species closely related to the endangered fresh water mussel Margaritifera auriculariais. Life cycle of the mussel requires a fish, such as the Glochidium parasiticum., Experiments for captive breeding of the mussel are being done with native fish species Salaria fluviatilis (blenny), but also trials are being conducted with Acipenser sturio..