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Postlarvae (PL) of Macrobrachium rosenbergii (de Man 1879) were stocked at 1, 2, 3 and 4 PL m−2. Prawns were fed only pellets (P) and a combination of pellets and snail meat (PS) with three replications in 100 m2 plots in the rotational prawn–rice system. Water levels were 0.3–0.6 m in rice growing areas. The water temperatures at noon in the hot months were higher than the suitable range for prawns. The final mean weights of prawns in treatments 1, 2 and 3 PL m−2 were significantly higher than in treatment 4 PL m−2 ( P<0.05). The yields from different density treatments ranged from 194±82 to 373±32 kg ha−1 and increased significantly with the increases in prawn densities ( P<0.05). There was no significant difference between the two types of feed on production parameters ( P>0.05). The total cost significantly increased at higher densities ( P<0.05), but it was not different between feed types ( P>0.05). Net profit and cost benefit ratio of treatment PS were significantly higher than in treatment P. In the present study, treatment 3 PL m−2 and treatment PS offered the optimal results. [ABSTRACT FROM AUTHOR]

Post larvae of Macrobrachium rosenbergii (de Man 1879) were stocked at 2, 4, and 6 postlarvae (PL)/m2 into rice fields under two culture systems, the integrated and the rotational prawn-rice system. Prawn was fed pellet feed twice daily. The growth of Macrobrachium rosenbergii decreased at higher stocking densities. Prawns in the rotational system grew faster than those in integrated system. The yields ranged from 286 ± 32 to 527 ± 51, 412 ± 17, to 538 ± 37 kg/ha in the integrated and the rotational prawn-rice system, respectively. The yield at density of 2 PL/m2 was significantly lowest (P < 0.05) and was highest in the treatment with 6 PL/m2. However, at higher density, the investment cost significantly increased (P < 0.05), while profit significantly decreased (P < 0.05). At a density of 2 PL/m2, cost benefit ratio and profit was the highest (P < 0.05). The integrated rice-prawn system gives lower profits than the rotational system. [ABSTRACT FROM PUBLISHER]