Vibrio is one of the causes to high mortality in post-larvae (PL) tiger shrimp and PL white leg shrimp in hatcheries. This study has identified concentrations of Vibrio bacteria in the water can cause diseases on PLs in (1.47 - 5.51) x 10 exponent 2 cfu/ml, with death rates more 50 percent. The rates of Vibrio with phage in PL tiger shrimp and white leg shrimp in the hatcheries in central Vietnam, accounting for 2.9 percent of the 69 samples analysed. The phage of Vibrio alginolyticus was infected on PLs has reduced the number of bacterial infections on the shrimp. The impact of the risk environmental conditions is such as high temperatures, high salinity or cypermethrin toxic. It showed that risk environmental conditions have effects on death rates PLs in the experiments.