Grass carp (Ctenopharyngodon idella) is a freshwater, brackish species recorded in Hong Kong, Taiwan, United States. It is found at depths of 0–30 m. The main season in Hong Kong, Taiwan, United States runs all year.
Scientific name: Ctenopharyngodon idella · Water: Freshwater, Brackish · Season: All year
Size: up to 150 cm
Weight: up to 45 kg
The Grass carp is the only living member of the genus Ctenopharyngodon: a torpedo-shaped, large-scaled fish, dark olive above and yellow-brown on the flanks, with ridged pharyngeal teeth that let it graze aquatic plants and eat close to three times its own body weight a day; it tolerates 0 to 38 °C, salinity to 10 ppt and oxygen down to 0.5 ppm. Introduced to Taiwan long ago, it now works western Taiwan's large rivers and reservoirs, and its size, past 1.5 m, makes it a big-fish target in reservoirs and big rivers. In the United States it arrived in 1963, shipped from Taiwan and Malaysia to facilities in Alabama and Arkansas; the first escape is attributed to the Stuttgart, Arkansas experimental station in 1966, and by the 1970s it was in 40 states, now reported from 45, with natural reproduction confirmed in the Great Lakes basin in 2013. Sterile triploid fish are still stocked by many states to clear nuisance weeds. Because it is a wary vegetarian, rod catches are rare, so Americans shoot them by bowfishing or soak corn, dough balls or mulberries on the bottom, and late spring through summer, when water reaches 20 to 30 °C, is the productive window. Maximum about 150 cm total length and 45 kg, though some references give 2 m, and the rod-and-line world record stands at 39.75 kg, taken in Bulgaria in 2009. Lifespan is about 21 years. IUCN lists it as Least Concern.
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