Cystobranchus is a genus of leeches (Hirudinea) belonging to the family Piscicolidae.

[1] These leeches are associated with freshwater fishes, and closely related to the genus Piscicola.

[3] They are distributed in Europe and North America.

They attach themselves on the external part of fish and feed on their blood, which could cause the fish to be more suspectable to stressors and diseases.

[3] This annelid-related article is a stub.