Grass carp
Encyclopedia
The grass carp is a herbivorous, freshwater
fish
species of family Cyprinidae, and the only species of the genus Ctenopharyngodon. It is cultivated in China
for food, but was introduced in Europe
and the United States
for aquatic weed control (see, e.g., Ponchatoula Creek). It is a large cyprind native to eastern Asia, with a native range from northern Vietnam to the Amur River on the Siberia-China border. It is a fish of large, turbid rivers and associated floodplain lakes, with a wide degree of temperature tolerance. Grass carp are usually thought to enter reproductive condition and spawn at temperatures of 20 to 30 °C (68 to 86 F), but have been shown to sometimes spawn at temperatures as low as 15 °C (59 °F).
In the United States, the fish is also known as white amur, a name developed to avoid use of the name "carp", which has derogatory connotations in North America. The name derives from the Amur River, where the species is probably native, but has never been abundant. This is not to be confused with the white amur bream (Parabramis pekinensis), which is not a particularly close relative as Cyprinidae.
For eating, the fish may be steamed
, pan-fried
, broiled, or baked
.
Grass carp have elongate, chubby, torpedo-shaped body forms. 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 grass carp grows very rapidly, and young fish stocked in the spring at 20 centimetres (7.9 in) will reach over 45 centimetres (17.7 in) by fall, and adults often attain nearly 1.2 metres (3.9 ft) in length and over 18 kilograms (39.7 lb) in weight. According to one study, they live an average of five to 9 years, with the oldest gaining 11 years. They eat up to three times their own body weight daily. They thrive in small lakes and backwaters that provide an abundant supply of freshwater vegetation.
Adults of the species feed primarily on aquatic plants. They feed on higher aquatic plants and submerged terrestrial vegetation, but may also take detritus
, insect
s, and other invertebrate
s.
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.
The grass carp is considered an invasive species in the United States; however, it is still stocked in many states as an effective biocontrol for undesirable aquatic vegetation, many species of which are themselves invasive. Grass carp require long rivers for the survival of the eggs and very young fish.
in 1973 for overabundant aquatic weed control. The release into national waters is controlled and regulated by the Dutch Ministry of Agriculture, Nature and Food Quality. Because grass carp mainly reproduce in water of 25 °C (77 °F), which is much higher than the water temperature reaches during the mating season in the Netherlands, it is necessary to maintain grass carp populations by artificial means, which is done by the person responsible for the water body in which the fish were introduced. Where grass carp populations are maintained through stocking as a biocontrol for noxious weeds, they should be returned to the water alive and unharmed.
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 a rapid change in temperature or pressure. This process is not usually 100% effective, therefore, in the United States, the young are usually tested for triploidy before being sold. Bait often consists of vegetables or fruits that are native to the area.
with corn adds to success. Canned corn, cherry tomatoes, and, despite their primarily vegetarian habits, grass carp sometimes eat other vegetarians. Chumming with white bread, and a piece of bread pinched on a hook and floated on the surface works well, especially for pond grass carp. The fish are popular but wary quarry for bowfishers where bowfishing for grass carp is legal.
When searching for grass carp to fish, one may often spot fish cruising near the surface or very close to the shoreline. Often, an angler will spot a telltale swirl in the water near the shore without even glimpsing the fish. Grass carp often feed or rest near the shoreline, and are very wary in such places. They usually will dart away at the first sight of a person walking nearby. Stalking the fish to place a piece of bait nearby is sometimes successful. Casting bait on top of the fish usually results in spooking the fish.
Grass carp caught in ponds and lakes where they were stocked for weed control should be handled with care and released without harm.
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
species of family Cyprinidae, and the only species of the genus Ctenopharyngodon. It is cultivated in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
for food, but was introduced in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
for aquatic weed control (see, e.g., Ponchatoula Creek). It is a large cyprind native to eastern Asia, with a native range from northern Vietnam to the Amur River on the Siberia-China border. It is a fish of large, turbid rivers and associated floodplain lakes, with a wide degree of temperature tolerance. Grass carp are usually thought to enter reproductive condition and spawn at temperatures of 20 to 30 °C (68 to 86 F), but have been shown to sometimes spawn at temperatures as low as 15 °C (59 °F).
In the United States, the fish is also known as white amur, a name developed to avoid use of the name "carp", which has derogatory connotations in North America. The name derives from the Amur River, where the species is probably native, but has never been abundant. This is not to be confused with the white amur bream (Parabramis pekinensis), which is not a particularly close relative as Cyprinidae.
For eating, the fish may be steamed
Steaming
Steaming is a method of cooking using steam. Steaming is considered a healthy cooking technique and capable of cooking almost all kinds of food.-Method:...
, pan-fried
Pan frying
Pan frying is a form of frying characterized by the use of minimal cooking oil or fat ; typically using just enough oil to lubricate the pan...
, broiled, or baked
Baking
Baking is the technique of prolonged cooking of food by dry heat acting by convection, and not by radiation, normally in an oven, but also in hot ashes, or on hot stones. It is primarily used for the preparation of bread, cakes, pastries and pies, tarts, quiches, cookies and crackers. Such items...
.
Appearance and anatomy
The grass carp grows very rapidly, and young fish stocked in the spring at 20 centimetres (7.9 in) will reach over 45 centimetres (17.7 in) by fall, and adults often attain nearly 1.2 metres (3.9 ft) in length and over 18 kilograms (39.7 lb) in weight. According to one study, they live an average of five to 9 years, with the oldest gaining 11 years. They eat up to three times their own body weight daily. They thrive in small lakes and backwaters that provide an abundant supply of freshwater vegetation.
Ecology
This species occurs in lakes, ponds, pools and backwaters of large rivers, preferring large, slow-flowing or standing water bodies with vegetation. In the wild, grass carp spawn in fast-moving rivers, and their eggs, which are slightly heavier than water, develop while drifting downstream, kept in suspension by turbulence. The eggs are thought to die if they sink to the bottom.Adults of the species feed primarily on aquatic plants. They feed on higher aquatic plants and submerged terrestrial vegetation, but may also take detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, and other invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s.
Invasive species
The species was deliberately introduced into the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in 1963 for aquatic weed control. It was introduced into New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
along with stocks of goldfish
Goldfish
The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....
, but the distribution is carefully controlled to prevent it from becoming a more widespread pest.
The grass carp is considered an invasive species in the United States; however, it is still stocked in many states as an effective biocontrol for undesirable aquatic vegetation, many species of which are themselves invasive. Grass carp require long rivers for the survival of the eggs and very young fish.
Use as weed control
The species was introduced in the NetherlandsNetherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
in 1973 for overabundant aquatic weed control. The release into national waters is controlled and regulated by the Dutch Ministry of Agriculture, Nature and Food Quality. Because grass carp mainly reproduce in water of 25 °C (77 °F), which is much higher than the water temperature reaches during the mating season in the Netherlands, it is necessary to maintain grass carp populations by artificial means, which is done by the person responsible for the water body in which the fish were introduced. Where grass carp populations are maintained through stocking as a biocontrol for noxious weeds, they should be returned to the water alive and unharmed.
When used for weed control, often the fish introduced to the pond or stream are sterile, triploid
Polyploidy
Polyploid is a term used to describe cells and organisms containing more than two paired sets of chromosomes. Most eukaryotic species are diploid, meaning they have two sets of chromosomes — one set inherited from each parent. However polyploidy is found in some organisms and is especially common...
fish. The process for producing triploid fish involves shocking eggs with a rapid change in temperature or pressure. This process is not usually 100% effective, therefore, in the United States, the young are usually tested for triploidy before being sold. Bait often consists of vegetables or fruits that are native to the area.
Fishing for grass carp
Grass carp grow large and are strong fighters on a rod and reel, but because of their vegetarian habits and their wariness, they can be difficult to catch. ChummingChumming
Chumming is the practice of luring animals, usually fish or sharks, by throwing "chum" into the water. Chum often consists of fish parts and blood, which attract fish, particularly sharks due to their keen sense of smell....
with corn adds to success. Canned corn, cherry tomatoes, and, despite their primarily vegetarian habits, grass carp sometimes eat other vegetarians. Chumming with white bread, and a piece of bread pinched on a hook and floated on the surface works well, especially for pond grass carp. The fish are popular but wary quarry for bowfishers where bowfishing for grass carp is legal.
When searching for grass carp to fish, one may often spot fish cruising near the surface or very close to the shoreline. Often, an angler will spot a telltale swirl in the water near the shore without even glimpsing the fish. Grass carp often feed or rest near the shoreline, and are very wary in such places. They usually will dart away at the first sight of a person walking nearby. Stalking the fish to place a piece of bait nearby is sometimes successful. Casting bait on top of the fish usually results in spooking the fish.
Grass carp caught in ponds and lakes where they were stocked for weed control should be handled with care and released without harm.
External links
- Species Profile- Grass Carp (Asian Carp) (Ctenopharyngodon idella), National Invasive Species Information Center, United States National Agricultural LibraryUnited States National Agricultural LibraryThe United States National Agricultural Library is one of the world's largest agricultural research libraries, and serves as a National Library of the United States and as the library of the United States Department of Agriculture...
. Lists general information and resources for Grass Carp.