Biology of the European bitterling Rhodeus sericeus (pisces: cyprinidae) in the Bronx River,New York,USA: An apparently benign exotic species

Selected aspects of the biology of the European bitterling Rhodeus sericeus in southern New York were investigated as a preliminary determination of the impact of this species on the native ecosystem. There are about 900 bitterlings in the only extant North American population. The oldest specimen was in its fourth summer (III +) and all were mature in their first year. Fecundity is low, less than 60 eggs per female. Bitterlings feed primarily on diatoms and the digestive system is typical of a surface-scraping herbivore. Impact of this exotic species on the ecosystem appears minimal. It is unlikely that the species would cause appreciable negative impact on any habitat in the northeastern United States.