Success Stories In Asian Aquaculture - Library - Network of ...

2 Recent Developments in Rice-Fish Culture in China25Peripheral trenchlnletWatersupplyDrainagePaddy plotFish PitCentral cross trenchOutletPeripheral trenchField ridgeFig. 2.3 Layout of ridge-plot-trench rice–fish system2.6.2 Alternate Rice–fish Farming SystemsIn some rice–fish culture systems, instead of concurrent rice–fish culture, rice plantationand fish culture are conducted alternately in the same field. Rice plantationand fish culture may be conducted alternately by crop or annually. Compared withconcurrent rice–fish culture systems, rice and fish do not have close symbioticrelationship in alternate farming systems. However, alternative rice plantation andfish culture are beneficial to each other in many aspects. Alternative rice–fish cultureis relatively easy and does not require extensive earthwork to modify the structureof the field. It is more suitable for fish species that require deep water and alonger culture period.To conduct alternate rice–fish farming, the major requirements to rice fieldinclude reinforced rice field ridge, increased height of the field ridge (around 1 m),and a seepage free ridge.The alternate rice–fish culture usually includes one crop of rice followed by onecrop of fish within a year. The fish production usually ranges between 1,500 and3,000 kg/ha or even higher depending on species and feeding. The stocking of fishis usually carried out immediately after the preparation of the field where the riceis harvested in October. The rice straw is buried into soil as fertilizer and feed forfish. The fish is usually harvested in June before transplantation of rice seedlings.In both concurrent and alternate rice–fish systems, water inlet and outlet are positioneddiagonally and well fenced with screens of appropriate mesh-size dependingon stocking size of the cultured animals.