Synergistic approach in carp polyculture with grass carp as a major component

Using either phosphatic or nitrogenous fertilizers and aquatic weeds, yields of the order of 9.7 – 12.3 kg and 13.5 – 14.7 kg per ha per day were realised in 1981 and 1982, respectively, in carp polyculture at input costs of Rs 1.13-Rs 1.77 (US $ 0.09 – 0.15). High yields ranging from 12.3 to 15.1 kg per ha per day were also obtained with aquatic weeds alone at remarkably low input costs of Rs 0.93-Rs 1.42 (US $ 0.08 – 0.12) per kilogram of fish when grass carp ( Ctenopharyngodon idella) was the dominant species. The newly developed, low cost, labour intensive, technology could be recommended for extensive adoption in rural areas, especially in the Third World, where submerged aquatic vegetation such as Hydrilla, Potamogeton and Ceratophyllum or terrestrial vegetation like grasses or fodder are abundantly available.