SEED PRODUCTION OF GANGETIC PRAWN, MACROBRACHIUM GANGETICUM (BATE), IN NATURAL SEAWATER AND BRINE SOLUTION

Abstract

Larval rearing of Macrobrachium gangeticum was carried out under hatchery condition using natural seawater and concentrated brine solution for two successive years. Both the media were prepared by diluting with freshwater to maintain 12 ppt salinity. First zoea larvae were stocked @ 100 larvae/l in 300L plastic tanks adopting airlift biofilter re-circulatory system. Larvae were fed with Artemia nauplii twice daily for one week, thereafter egg custard and mussel meat at six hourly intervals including Artemia nauplii during night. Desired water quality parameters were maintained throughout the rearing period. Larvae passed through eleven distinct larval stages and first post-larvae (PL) appeared between day 19 and 22 in both the media and cycle was completed on day 40. The production of PL ranged from 8,726-9,009 with density of 29-30 PL/l during first year and 7,744-8,905 with density of 26-30 PL/l during second year in natural sea water. Almost similar trend in PL production was also recorded in brine solution too as it ranged from 6,498-7,825 with density of 22-26 PL/l during first year and 6,000-7,096 with density of 20-24 PL/l during second year. Though slightly higher production of PL was observed in the natural seawater, brine solution may be used in the operation of inland hatchery for PL production of Gangetic prawn .