Socialist Federal Republic of Yugoslavia
Regarding rivers, the Danube was navigable throughout its entire course in Yugoslavia, linking the ports of Belgrade, Novi Sad, and Vukovar with Central Europe and the Black sea. Long stretches of rivers Sava, Drava and Tisza were also navigable.
Danube barbel
The Danube barbel ("Barbus balcanicus") is a species of freshwater fish widespread in southeastern Europe. It is difficult to diagnose from e.g. "Barbus carpathicus" and "Barbus petenyi" in the field.