Gher is modified rice field (usually situated in flood plain) comprising a trench around the rice field and built up dikes to maintain a depth of around 1 meter in the trench. Farming of prawn (Macrobrachium rosenbergii) is became popular in south west Bangladesh during the 1980’s and as the price for prawn continued to rise, many farmers made costly investments in converting their rice fields into Gher. At present different categories of land and water bodies of approximately 50,000 ha are used in prawn aquaculture (Annual report-DoF, 2005-06).
In Bangladesh different culture systems are being practiced, such as-prawn monoculture, prawn polyculture along with other fishes (mostly carps), prawn aquaculture in paddy fields along with paddy, prawn aquaculture in paddy fields after paddy harvesting. In most culture system, horticulture crops are produced on dikes and slopes of the dike (Annual report-DoF, 2005-06). The sector (Fisheries) is the second largest source of export earnings, selling to major markets in the UK, Netherlands, Belgium and France. Export income of Bangladesh from prawn and shrimp was TK. 2281.59 crore in year 2004-05 (DoF, 2005).