Rice±fish culture systems in the freshwater area
of the Mekong Delta are mainly characterized by the
concurrent culture of rice and fish. One fish cycle
usually spans two rice crops (each rice crop about
100 days) and a rice ratoon crop. Ratooning is the
ability ofthe rice plantto regenerate new tillers after
harvest (Chauhan, Vergara & Lopez 1985). Because
ratooned rice has a shorter growth duration than a
new rice crop, farmers chose rice ratooning when
hydrological or climatic conditions do not allow for
another normally seeded rice crop.