Comparison of Production Characteristics of Freshwater Prawn, Macrobrachium rosenbergii, Stocked as 30 and 60 Day Nursed Juveniles

In temperate regions, prawns are typically stocked as nursed juveniles, which have been grown to advanced sizes over a 60 day nursery period prior to pond stocking. This allows the prawns to reach market size within the 110-150 day period of suitable pond temperature. However, the cost of the juveniles is directly related to the duration of the nursery period. If prawn juveniles could be nursed for only 30 days, this would greatly reduce their cost to the grow-out farmer. A 110-day pond study was conducted to evaluate the growth and survival rates of juvenile prawn stocked as 30 day nursed juveniles (0.1 g) and as 60 day nursed juveniles (0.8 g). Prawn were stocked at a rate of 62,000/ha into each of six 0.04 ha ponds. There were 3 replicate ponds per treatment. Prawns were fed a sinking shrimp feed (45% protein,15% fat) 2 times daily. At harvest, prawns stocked as 60 day juveniles had significantly higher (P \u3c 0.05) average harvest weight (37 g), survival (96%) and production (2,497 kg/ha) than juveniles stocked as 30 day juveniles, which averaged 24 g average weight, 74% survival, and 1,272 kg/ha total production. These data indicate that 30 day nursed juveniles do not perform as well as those nursed for 60 days