5 Euros Danube salmon

Slovakia's "Nature Protection" collector series has addressed indigenous freshwater species before, but the Danube salmon — known locally as the hlavátka podunajská — occupies a specific conservation urgency that others in the series do not. The fish is functionally extinct in much of its historic Slovak range, surviving in viable numbers only in the Váh and a handful of its tributaries, largely due to hydroelectric damming through the second half of the twentieth century.

KM#221 is a bimetallic-adjacent brass circulation-quality issue rather than a silver proof, placing it in a more accessible tier of the series.