Development of rice-fish system: Today and tomorrow

Land and freshwater resources are essential for ensuring global sustainable food supplies. The world agriculture currently faces great challenge on how to secure food supply with scarce land and freshwater resources without negatively impacting the environment. Rice-fish system (where 'fish' denotes a wide range of aquatic animals including fish, prawn, shrimp, crabs, soft shell turtles, etc.) is one of the successful models for producing both rice and fish by efficient use of land and freshwater resources. Rice-fish system has contributed to local food security, poverty alleviation and environmental conservation. In the last decades, rice-fish system experienced a fast development in the world. Recently, rice-fish system is practiced in 28 countries (including Japan, Egypt, India, Indonesia, Thailand, Vietnam, Philippines, Bangladesh, Myanmar and Malaysia). Rice-fish system has a long history in China and has played an important role in providing rice and fish for local consumption. Over the last 60 years, Chinese rice-fish system has steadily developed and changed from small-scale traditional farming to large-scale modern farming with specialization and commercialization to ensure sustainability. Studies have shown that rice-fish system can have high yields of rice and fish and thereby optimizes the benefits of scarce land and water resources as a result of complementary and synergistic interactions between fish and rice. Rice-fish system also decreases pesticide use due to lowering the incidence of diseases, insect pests and weeds in rice fields. Meanwhile, rice-fish system reduces nitrogen fertilizer application through complementary use of nitrogen by rice and fish, and enhances soil nutrient availability for rice crop. Rice-fish system also resolves certain problems induced by freshwater aquaculture because nutrients in effluents resulting from fish production are absorbed by rice crops and are therefore not wasted or would not become a pollution source. Although most areas of global rice fields are suitable for developing rice-fish system, the adoption rate and scale of rice-fish system in the world remain low. In China, there is only 4.48% of the total well-irrigated rice paddies co-cultured with fish. Therefore, to ensure sustainable development of rice-fish system, more efforts are needed. These efforts include: 1) potential assessment of rice paddy for rice-fish system (e.g. water supply and water quality in rice fields), evaluation of new fish species for rice field culture and selection of rice varieties for rice-fish co-culture; 2) development of technology packages for culturing rice and fish, optimization of fertilization rates and fertilization methods for rice and optimum feeding rates and methods for fish; 3) developing field configurations for rice culture and aquaculture; 4) optimization of rice planting patterns for rice-fish farming, determination of the carrying capacity and optimization of stocking densities; 5) development of suitable machines for rice-fish system; and 6) assisting farmers to create identity product brands acceptable to consumers and society.