The grass carp, Ctenopharyngodon idella Cuvier and Valenciennes, was imported to the U.S. in 1963 as a biological control agent for hydrilla (Hydrilla verticilliata (L.f.) Royle) and other aquatic plants. Concerns of escape and reproduction, and the potential impacts that colonization of the fish could have on native flora and fauna led to research that developed a non-reproductive fish, which was equally effective in controlling hydrilla. In the warm waters of Florida, with abundant food, grass carp grow quickly at around 2 lbs/month or 0.91 kg/month and may achieve weights of 97 lbs (44 kg). Younger fish and female fish grow faster than older or male fish. Grass carp are the most effective biological control tool that has been identified for hydrilla. This 7-page fact sheet was written by Emma N.I. Weeks and Jeffrey E. Hill, and published by the UF Department of Entomology and Nematology, June 2014.
http://edis.ifas.ufl.edu/in1038