CULTURE OF MACROBRACHIUM-ROSENBERGII IN MONOCULTURE AND POLYCULTURE WITH OREOCHROMIS-NILOTICUS IN PADDIES IN EGYPT

Production of Macrobrachium rosenbergii and Oreochromis niloticus ir 7 ,200 m(2) paddies was evaluated. The stocking density of the prawn mon oculture was 10,000 and 20,000 prawn juveniles per hectare. In the pol yculture system, 10,000 prawn juveniles and 5,000 Nile tilapia fingerl ings per hectare were stocked. Rice paddies with no prawn or fish were used as controls in a replicate experiment. The mean prawn yields aft er 90 days of culture using the monoculture system were 429.0 and 844. 6 kg/ha for the low and the high stocking densities, respectively. In the polyculture system, the mean yield was 254.0 kg prawns plus 754.4 kg Nile tilapia per hectare, The mean prawn harvest weight was 48.4-45 .9 g in the monoculture system and 30.3 g in the polyculture. The mean harvest weight of the Nile tilapia was 160.5 g. The mean rice crop wa s 8,806 and 8,722 kg/ha in the monoculture, 8,605 kg/ha in the polycul ture and 7,378 kg/ha in the control fields.Total production costs per hectare were estimated to be US$2,432 and 3,318 in the rice-prawn fiel ds,US$2,797, in rice-prawn-fish fields and US$1,161 in the control. Th e maximum net return per hectare was US$4,507, obtained in high densit y rice-prawn culture, while the rice only treatment gave the lowest ne t return, US$904 per hectare.