Grasses that grow with rice absorb available fertilizer and compete for nitrogen. Fish excrement, in turn, fertilizes the rice, increases organic matter in the soil, and improves the fertility of the ricefield. Pests and plant diseases. When insects move about in the water, or when their eggs fall into the water, they are eaten by the fish. In this way, fish raising benefits the rice because it reduces plant diseases and eliminates pests.
Fish also help rid rice plants of surplus tillers and disease-ridden leaves.
This increases the penetration of light and reduces the occurrence of plant diseases and pests. In addition, the movements of fish stir the water and soil, which increases oxygen in the water, speeds the release of fertilizer in the soil, and improves the development of the root system of the rice. Loosening the soil, eliminating weeds, and adding fertilizer raises rice production in many ways. The need to weed by hand is eliminated and reduced amounts of chemical fertilizer and insecticide are needed. These benefits produce savings in labour and investments and help improve the rural environment and the health of the people.