The lake minnow or swamp minnow (Rhynchocypris percnurus) is a species of freshwater ray-finned fish belonging to the family Leuciscidae, which includes the daces, chubs, true minnows and related fishes. It has a wide but disjunct distribution including parts of Europe (Belarus, Czech Republic, Germany, Lithuania, Poland, Russia, and Ukraine) and Asia (northern China, Japan, Korea, and Siberia).
Individuals in this species can grow up to .