Sometimes a grass carp may be referred to as a white amur.

SCIENTIFIC NAME: Ctenopharyngodon idella
Grass carp belong to the Cyprinidae family, the minnows and the carps. Its genus Ctenopharyngodon is made up of the Greek word "ktenos" meaning "comb", the Greek word "pharynx" meaning "throat", and the Greek word "odous" meaning "teeth". Referring to this fish's pharyngeal teeth. The grass carp was first described by Valenciennes in 1844.

DISTRIBUTION: Grass carp are natively from eastern Asia from the Amur River in Russia to the West River in southern China. Currently the grass carp's range has significantly increased. It has been introduced into about 70 countries around the world including the United States. The grass carp can now be found in 45 states.

DESCRIPTION: The grass carp has an oblong body, a round belly and a broad head. Above its color is a silvery dark grey and the sides are lighter with a gold sheen and the belly is whitish. The dorsal fin begins in front of the fish's pelvic fins. It has large scales that resemble a chain link fence. There are no teeth in the grass carp's jaw but it does have pharyngeal teeth. The maximum-recorded length of a grass carp is 5 feet and the maximum-recorded weight is 100 pounds.

PATHWAYS/HISTORY: In 1963 the grass carp was introduced into aquaculture facilities in Alabama and Arkansas. The first report of these fish escaping into open waters was in 1984 from the facility in Arkansas. Though stocking had been made in Arkansas into lakes that were open to stream systems. By 1970 there were reports of grass carp being caught in the Mississippi River and the Missouri River. From here the grass carp was being sighted all over it was being continually stocked into new waters. Now there are recorded grass carp sightings in Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin, and Wyoming. Established populations of grass carp can be found in Arkansas, Kentucky, Illinois, Louisiana, Missouri, Mississippi, Tennessee, Texas and Minnesota.

DISPERSAL/SPREAD: Originally grass carp were introduced into farm ponds to control aquatic vegetation. They have escaped these ponds due to flooding and moved into open waters. Stocking of grass carp is very common. Some stocking have occurred in lakes with access to rivers and streams, this has allowed the grass carp to spread into new waters. Federal and state agencies have participated in stockings as well as private pond owners. Escapees from these introductions have contributed to the rapid range expansion of the grass carp.

MANAGEMENT: To try to control the spread of grass carp all 50 states have restrictions on their use. There was an effort to try to create all female populations so that no breeding would take place. These females were still fertile so if there happened to be an accidental introduction of a male, they could become a reproducing population. Since then scientists have tried to create triploid individuals that would be sterile and therefore they would be unable to breed. Alaska, Oregon, Montana, North Dakota, Minnesota, Wisconsin, Michigan, Massachusetts, Vermont, Maine, Maryland and Rhode Island all prohibit any form of grass carp. Hawaii, Iowa, Kansas, Missouri, Oklahoma, Arkansas, Mississippi and Alabama have no restrictions at all on grass carp. All of the remaining states have some form of restrictions regarding grass carp as of 1994.

SPECIAL INTEREST: Grass carp are legal to stock in Indiana as long as they are triploid, unable to breed. Visit the Indiana Department on Fish and Wildlife's website for a list of Indiana dealers who sell triploid grass carp.

LIFE CYCLE BIOLOGY AND LIFE HISTORY: The grass carp can occur in lakes, ponds, pools and backwaters of large rivers. It prefers to have large standing or slow-flowing water with vegetation. They are a hearty species that can tolerate temperatures from freezing to over 100o F., brackish water, and low oxygen situations. Female carp release their eggs when the water temperature is between 18o F and 23o F, and when the water level is rising. The eggs must remain suspended until they hatch to survive. The maximum age of a grass carp is 21 years old. Grass carp primarily eat aquatic vegetation but they will eat detritus, insects and other invertebrates if vegetation is scarce. Because they eat aquatic plants grass carp are frequently stocked as a biological control of vegetation.

RISKS/IMPACTS: In large numbers grass carp can remove all aquatic vegetation from the water. If they do so they eradicate habitat for invertebrates and juvenile fishes. It also eliminates the food base for other fishes and it remove all the forage for waterfowl. In a lesser density of grass carp they can be selective feeders, which increases the toxic plants availability. This can result in algae blooms that can reduce the oxygen level in the water. They also compete with invertebrates and fishes for food. They have the ability alter the plant community, which can in turn completely change the invertebrate community and the fish community. One more risk that grass carp pose is that it may be carrying a parasite or disease that could be transmitted to our native fishes.

- Agbayani, Eli. Ctenopharyngodon idella: Grass Carp. 19 May 2004. Fishbase. 27 May 2004.
- Asian Carp. 11 Nov. 2002. U.S. Fish and Wildlife Service. 27 May 2004.
- Ctenopharyngodon idella. 21 Nov. 2003. Gulf States Marine Fisheries Commission. 27 May 2004.
- Grass Carp. Florida's Fish and Wildlife Conservation Commission. 27 May 2004.
- Nico, Leo and Pam Fuller. Ctenopharyngodon idella. 1 April 2001. U.S. Geological Survey. 27 May
- Seng, Phil, and Gwen White. Indiana Aquatic Nuisance Species Management Plan. 1 Oct. 2003.
  Indiana Department of Natural Resources. 27 May 2004.

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