The study was conducted at the farmer's pond at Sadar Upazilla of Bagerhat District, South-west coastal region of Bangladesh during the period from May 2006 to April 2007 to understand the present status of crop rotation practice and assess the production and cost benefit ratio of the existing culture practices. Two treatments viz., the crop rotation with paddy (T 1 ) and the shrimp-prawn-fish culture (T 2 ) were used in the studies. Shrimp (Penaeus monodon), prawn (Macrobrachium rosenbergii), and catla (Catla catla) were stocked at 20000, 10000, and 250 individuals/ha, respectively, in both treatments. In T 1 , aquaculture phase was from May to December 2006, and the episode of paddy (BRRI dhan 28) cultivation was initiated after full harvest of aqua products and continued till April. Similar farm inputs were given for the common components in both the treatments. Shrimps were harvested four months following stocking in both T 1 and T 2 treatments. . In T 1 , production of shrimp, prawn, and catla were 347.20, 355.35, and 140.4 kg/ha, respectively and in T 2 , productions were 354.38, 432.37, and 204.7 kg/ha, respectively. In T 1 , total paddy production was 6200 kg/ha. Net benefit in T 1 and T 2 was Tk. 300,477 and Tk. 262,561/ha, respectively.

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Mud crab (Scylla spp.) aquaculture has become an important livelihood option for the coastal fisher-folks in Bangladesh. Mud crabs harvested from wild sources are traditionally fattened in pens installed in tidal rivers, ghers, and earthen ponds in Bangladesh. The study was aimed at understanding the practice and production economics of mud crab farming in the South-West Sundarbans region of Bangladesh, and was conducted in the areas namely Bagerhat, Satkhira and Khulna districts where mud crab fattening are predominately ventured. Most of the farmers fatten both male (lean) and female (gonadally immature) crabs of 100 - 180 g. The crabs are stocked at varying rate (12 - 641 g/m2), and fed at the rate of 8-10% of body weight with trash live fishes, dried fishes, snails, mollusks, and cattle viscera. The fattening for a mean cycle of 22 ± 14.34 days has the survival rate of 55 - 90%, and has the production of 0.065 ± 0.26, 0.084 ± 1.33, and 0.17 ± 3.76 kg/m2 in Bagerhat, Satkhira, and Khulna, respectively. After harvesting (mostly partial), crabs are sold at average price rate of 4.35 ± 0.45 US$/kg. The lowest production cost (3.14 US$/kg) and the better economic return (US$ 147.77) per cycle was recorded in the district of Satkhira. The mud crab fattening has hitherto been evaluated economically feasible in and around the Sundarbans region, but the production and economic efficiency can be scaled up adopting scientifically demonstrated regime of stocking, feeding, and health management. The development of crab seed hatchery, artificial feed for crab, and strongest marketing network are addressed as crux issues for the sustainability of mud crab aquaculture in Bangladesh.