The river mussel (Unio crassus, Philipsson, 1788) occurs predominantly in freshwaters, less frequently also in brackish Waters.
It used to be native to large rivers such as the Elbe, Rhine and Danube.
InCentral Europe, however, its distribution is now rather limited to upper reaches and smaller streams which lead to the German and Luxembourgian name “Bachmuschel” which means “stream mussel”.
Its common name in English is thick shelled river mussel.