Freshwater mussels play an important role in rosy bitterling reproduction. It also suffers from competition from the related but more aggressive rosy bitterling. Fish species include spined loach, European weatherfish and European bitterling. This and "Rhodeus smithii", sometimes called the Japanese rosy bitterling, were formerly considered conspecific. Since the rosy bitterling was introduced, their population has been increasing dramatically all over Japan. The common name for this species is Giant Chinese Bitterling because of its Chinese origin. The Tokyo bitterling ("Tanakia tanago") is a temperate freshwater fish of the carp family (Cyprinidae). The Amur bitterling ("Rhodeus sericeus") is a small fish of the carp family. The elongate bitterling ("Acheilognathus elongatus") is a species of freshwater fish in the family Cyprinidae. Properly, "bitterling" can refer to any species of "Acheilognathus" or "Rhodeus".