Potamilus fragilis, previously Leptodea fragilis, the fragile papershell, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels. P. fragilis is one of the fastest-growing unionid species and the most abundant unionid species in Lake Erie.[1] Its light-shelled morphology suggests an adaptation to deep water within lakes.
This species is found in the United States and Canada. Its natural habitats include streams, rivers and freshwater embayments.
A common host for the glochidia of this species is the freshwater drum (Aplodinotus grunniens).[2]