Grass carp
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| Grass Carp | ||||||||||||||||
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 Grass Carp - juvenile | ||||||||||||||||
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| Ctenopharyngodon idella |
The Grass Carp, (Ctenopharyngodon idella), also known as the White Amur, is a herbivorous, freshwater fish considered especially well suited for aquatic weed control. It is a species of carp native to Siberia and northern China. The name White Amur derives from the Amur river, where the species is believed to originate.
White amur have an elongate, chubby body form that is torpedo shaped (terete). The terminal mouth is slightly oblique with non-fleshy, firm lips, and no barbels. The complete lateral line contains 40 to 42 scales. Broad, ridged pharyngeal teeth are arranged in a 2, 4-4, 2 formula. The dorsal fin has 8 to 10 soft rays, and the anal fin is set closer to the tail than most cyprinids. Body color is dark olive, shading to brownish-yellow on the sides with a white belly and large slightly outlined scales.
The species was deliberately introduced into the United States in 1963 for aquatic weed control. It was introduced into New Zealand along with stocks of goldfish but the distribution is carefully controlled to prevent it from becoming a more widespread pest. Adults of the species feed exclusively on aquatic macrophytes. The grass carp grows veray rapidly, and young fish stocked in the spring at 8 inches will reach over 18 inches by fall, and adults often attain nearly 4 feet in length and over 40 pounds in weight.
When used for weed control, often the fish introduced to the pond or stream are sterile, triploid fish. The process for producing triploid fish involves "shocking" eggs with heat or electricity. The young are then tested for triploidy before being sold. In the wild, grass carp only breed in fast-moving rivers.bg:Бял амур de:Graskarpfen