Grass carp

The grass carp is the only extant member of the genus Ctenopharyngodon, but two other extinct species in the genus are known from Early Miocene-aged fossil teeth from China: †Ctenopharyngodon orientalis Su, Chang & Chen, 2021 (Xiacaowan Formation of Hebei) and †Ctenopharyngodon xiejiaensis Su, Chang & Chen, 2021 (Xiejia Formation of Qinghai). The earliest fossil teeth of the modern grass carp (C. idella) appear in the Early Pliocene-aged Gaozhuang Formation of Shanxi. Two other extinct genera that appear to be related to grass carp, †Eoctenopharyngodon and †Dezaoia, are known from the Oligocene of China. ==Description==

Grass carp have elongated, 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 eight to 10 soft rays, and the anal fin is set closer to the tail than most cyprinids. The 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 will reach over by fall. The typical length is about . The maximum length is and they grow to . ==Ecology==

Grass carp inhabit lakes, ponds, pools and backwaters of large rivers, preferring large, slow-flowing or standing water bodies with abundant vegetation. Adult grass carps feed primarily on aquatic plants, both higher aquatic plants and submerged terrestrial vegetation, but may also eat detritus, insects and other invertebrates. ==Introduced species==

Grass carp have been introduced to many countries around the world. In the Northern Hemisphere, countries and territories of introduction include Japan, the Philippines, Malaysia, India, Pakistan, Iran, Israel, the United States, Mexico, Sweden, Denmark, the United Kingdom, France, Germany, the Netherlands, Switzerland, Italy, Poland, the Czech Republic, Slovakia, Romania, Croatia, Slovenia, Serbia, Montenegro, Bosnia and Herzegovina and Macedonia. In the Southern Hemisphere, they have been introduced to Argentina, Venezuela, Australia, New Zealand, Fiji and South Africa. Grass carp are known to have spawned and established self-reproducing populations in only six of the many larger Northern Hemisphere rivers into which they have been stocked. Their failure to establish populations in other rivers suggests they have quite specific reproductive requirements. In the United States, the species was first imported in 1963 from Taiwan and Malaysia to aquaculture facilities in Alabama and Arkansas. Triploid grass carp (unable to reproduce) are still stocked as in many states as an effective biocontrol for undesirable aquatic vegetation, many species of which are themselves introduced. ==Use==

Weed control 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. They are now approved by the New Zealand government for aquatic weed control, although each instance requires specific authorization. In the Netherlands, the species was also introduced in 1973 to control over-abundant aquatic weeds. The release was controlled and regulated by the Dutch Ministry 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, Food 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 the black carp, silver carp, and bighead carp. Its meat is tender, with little bones. Many Chinese cuisine has grass carp as a featured dish, such as Cantonese cuisine. 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. Fishing 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 via angling. The IGFA World record for a grass carp caught on line and hook is , caught in Bulgaria in 2009. The fish are also popular sport fish in areas where bowfishing is legal. Where grass carp populations are maintained through stocking as a biocontrol for noxious weeds, fishermen are typically asked to return any caught to the water alive and unharmed. ==References==