Abstract: Cockspur (Echinochloa of Gramineae) is an aquatic or semi-aquatic plant widelydistributed in various parts of China. Since the year 1976, experiments of plantingcockspur in fish-pond and of submerging as green manure for the purpose of rearingfish fingerlings have been carried out. The fish yields range from 75 to 100kg/mu have been obtained without supplementary feeding or manuring. The paper deals with the techniques of planting cockspur and roaring fingerlingsin fish-ponds. An account of the dynamics of the concentrations of nitrogen andphosphorus in bottom mud and in water of the experimental ponds and of the liberationof nitrogen and phosphorus during the process of decomposition of cockspur and theinfluence on the abundance of planktons is given.