The paper studies the input-?output relationship in fish farming in India through the estimation of production function and the derivation of the optimum input combinations. It finds that fish farming is subject to constant returns to scale; production technology is far from the optimum application of the optimum production technique would reduce the production cost by about 33 percent and rise and if fish is attempted to achieve the maximum possible profit / hectare , the yield rate would multiply by about three time and the profit rate by over six times.