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. It is known simply as "the bitterling" in its native range, where it is the only species of its genus Rhodeus, and sometimes in the scientific literature, also, but this is technically wrong, being a leftover from the times when the European bitterling was united with its Siberian relative, the Amur bitterling, in R. sericeus. Properly, "bitterling" can refer to any species of Acheilognathus or Rho