شبّوط الأعشاب، مبروك الأعشاب Ctenopharyngodon idella

Grass carp, also called white amur, is a large cyprinid native to rivers of eastern China and the Amur system of eastern Russia, imported into the United States in 1963 as a biological control agent and now farmed in enormous volume, with FAO FishStat recording 6,439,159 tonnes in 2024. Adults eat higher aquatic plants and submerged grasses, and at about 20 degrees C an adult will consume its own body weight in hydrilla in a day. That appetite is both its polyculture role, taking the macrophyte niche beside the plankton-filtering silver and bighead carps and the bottom-feeding common carp, and the reason it is stocked for weed control at roughly 10 to 15 fish per hectare of lake. It spawns only in long, fast rivers at 20 to 30 degrees C, so it will not reproduce in ponds and all seed comes from hatchery propagation; where it is released into open water, sterile triploids are used. It tolerates salinity to 10 ppt and dissolved oxygen down to 0.5 ppm, which matters when handling and transporting it. Sources disagree on its maximum size, and its reported life is a usual five to nine years against a maximum beyond twenty.