Fish have been harvested from rice fields as an additional crop
since ancient times. Biologically, rice fields can be considered
as agriculturally managed marshes, which remain dry for varying
periods of time during the year. Physically, the aquatic phase
has varying water depth according to the land topography and
local rainfall patterns and water tables. In its flooded state, the
rice field is a rich and productive biological system which can
produce a crop of aquatic organisms, both plant and animal, for
human consumption in addition to the rice.