The European bitterling (Rhodeus amarus) is a temperate freshwater fish belonging to the Acheilognathinae subfamily of the Cyprinidae family. It originates in Europe, ranging from the Rhone River basin in France to the Neva River in Russia. It was originally described as Cyprinus amarus by Marcus Elieser Bloch in 1782, and has been referred to in scientific literature as Rhodeus sericeus amarus.