Grass carp have elongated, chubby, torpedo-shaped body forms. The terminal mouth is slightly oblique with non-fleshy, firm lips, and nobarbels.[5] The completelateral line contains 40 to 42 scales. Broad, ridgedpharyngeal teeth are arranged in a "2, 4-4, 2" formula. The dorsal fin has eight 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.
Grass carp grow very rapidly. Young fish stocked in the spring at 20 cm (7.9 in) will reach over 45 cm (18 in) by fall. The typical length is about 60–100 cm (23.5–39.5 in). The maximum length is 2.0 m (6.6 ft) and they grow to 45 kg (99 lb).
Grass carp inhabit lakes,ponds,pools andbackwaters of large rivers, preferring large, slow-flowing or standingwater bodies with abundant vegetation.[5] 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. Grass carp require long rivers for the survival of the eggs and very young fish, and the eggs are thought to die if they sink to the bottom.[6]
Adult grass carps feed primarily onaquatic plants, both higher aquatic plants and submerged terrestrial vegetation, but may also eatdetritus,insects and otherinvertebrates.[2][5] They eat up to three times their own body weight daily, and thrive in small lakes and backwaters that provide an abundant supply of vegetation.[citation needed]
According to one study, grass carp live 5–9 years, with the oldest surviving 11 years. InSilver Lake,Washington, a thriving population of grass carp is passing the 15-year mark.[7]
In the United States, the species was first imported in 1963 fromTaiwan and Malaysia to aquaculture facilities inAlabama andArkansas.[9] The first release is believed to have been an accidental escape in 1966 from theU.S. Fish and Wildlife Service's Fish Farming Experimental Station inStuttgart, Arkansas, followed by planned introductions beginning in 1969.[9][10] Subsequently, authorized, illegal and accidental introductions have been widespread; by the 1970s, the species had been introduced to 40 states, and it has since been reported in 45 of the country's 50 states.[9][10] In 2013, it was determined to be reproducing in theGreat Lakes Basin.[11] It is still stocked in many states as an effectivebiocontrol for undesirable aquatic vegetation,[9][10] many species of which are themselves introduced.
Grass carp were introduced into New Zealand in 1966 to control the growth of aquatic plants. Unlike the other introduced fish brought to New Zealand, the potential value and impact of grass carp was investigated in secure facilities prior to their use in field trials.[12] They are now approved by the New Zealand government for aquatic weed control, although each instance requires specific authorization.[13] In the Netherlands, the species was also introduced in 1973 to control over-abundant aquatic weeds. The release was controlled and regulated by the DutchMinistry of Agriculture, Nature, and Food Quality. In both of these countries, control is made easier because grass carp are very unlikely to naturally reproduce because of their very specific breeding requirements,[13] but elsewhere, control is obtained by the use of sterile,triploid fish.[10][14]
Global aquaculture production of Grass carp (Ctenopharyngodon idella) in million tonnes from 1950 to 2022, as reported by theFAO[15]
Grass carp is one of the most common freshwater farmed fish in China, being one of the Four Domestic Fish(四大家鱼) alongside theBlack carp,Silver carp, andBighead carp. Its meat is tender, with little bones. ManyChinese cuisine has grass carp as a featured dish, such asCantonese cuisine.[16] In some Asian countries, it is believed that ingestion of raw bile or entire gall bladders of the grass carp may improve visual acuity and health. However, it may in fact cause severe poisoning.[17]
Grass carp grow large and are strong fighters when hooked on a line, but because of their vegetarian habits and their wariness, they can be difficult to catch viaangling.[18] TheIGFA World record for a grass carp caught on line and hook is 39.75 kg (87.6 lb), caught inBulgaria in 2009.[19] The fish are also popularsport fish in areas wherebowfishing is legal.
Where grass carp populations are maintained throughstocking as a biocontrol for noxious weeds, fishermen are typically asked to return any caught to the wateralive and unharmed.
^Shireman, J.V. and C.R. Smith. 1983.Synopsis of biological data on the grass carp, Ctenopharyngodon idella (Cuvier and Valentines, 1844). Food and Aquaculture Organization Synopsis. 135: 86pp.
^Krykhtin, M.L., and E.I. Gorbach. 1981.Reproductive ecology of the grass carp, Ctenopharyngodon idella, and the silver carp, Hypophthalmichthys molitrix, in the Amur Basin. Journal of Ichthyology 21(2):109-123.
^Rowe, D. K., & Schipper, C. M. (1985).An assessment of the impact of grass carp (Ctenopharyngodon Idella) in New Zealand waters. Rotorua N.Z.: Fisheries Research Division, Ministry of Agriculture and Fisheries.
^abcdNico, L.G.; Fuller, P.L.; Schofield, P.J.; Neilson, M.E. (15 March 2012)."Grass Carp (Ctenopharyngodon idella)".Nonindigenous Aquatic Species (NAS) database. Gainesville, FL: United States Geological Survey. Retrieved12 January 2014.
^Chapman, Duane C.; Davis, Jeremiah J.; Jenkins, Jill A.; Kocovsky, Patrick M.; Miner, Jeffrey G.; Farver, John; Jackson, P. Ryan (2013). "First evidence of grass carp recruitment in the Great Lakes Basin".Journal of Great Lakes Research.39 (4):547–554.Bibcode:2013JGLR...39..547C.doi:10.1016/j.jglr.2013.09.019.ISSN0380-1330.
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