The grass carp (Ctenopharyngodon idella) is a large herbivorous freshwater fish species of the family Cyprinidae native to eastern Asia, with a native range from northern Vietnam to the Amur River on the Siberia-China border. Maximum size is over 4 feet and 80 pounds. It is cultivated in China for food, but was introduced in Europe and the United States for aquatic weed control in ponds and lakes. Unfortunately it has escaped from aquaculture facilities and has now become in limited areas a serious invasive species. Scientists have now produced a sterile triploid strain that is now the only form legal for stocking. Its requirement of long rivers for successful reproduction has also limited its spread. In the United States, the fish is also known as white amur, which is derived from the Amur River.