Abstract: A study was undertaken to evaluate the possibility of utilizing natural brackishwater (from Shibsa River) in the hatching operation and larvae culture of Macrobrachium rossenbergii. Three treatments each with three replications were tested. Natural brackish water diluting by rainwater (T1), natural brackishwater diluting by under ground tap water (T2) and natural brackish water with salinity range from 12 to 20 ppt. (T3) were considered. In case of dilution (in T1 and T2) salinity concentration range was maintain from 4-18 ppt as per requirement of the experiment and stage of brood and larvae. Significant higher survival (23.38%) for T1 was observed followed by T3 with 13.63% and T2 with 4.38% up to post larvae (PL) stage. Significant (p<0.05) difference in survival rate of larvae between T1 and T2 and T2 and T3 was observed. Study reveals that natural brackishwater diluting by rain water can be effectively used in the hatching operation and larvae culture of the freshwater giant prawn, M. rossnbergii.