All-male giant freshwater prawns (AMGFPs) have been a popular crop cultivated in the Mekong Delta, Vietnam due to their proven production efficiency compared to all-female or mixed-sex prawn culture. However, the crucial water quality factors impacting AMGFP aquaculture efficiency have yet to be elaborately investigated. Two separate experiments were randomly arranged with three replicates to evaluate the effects of salinity or alkalinity on the growth and survival of AMGFP juveniles during the grow-out period. The results show that the prawn survival rate in the salinity range of 0–15‰ varied from 66.1 to 74.8% and in the salinity range of 0 - 5‰ was  relatively low compared to the range of 10 - 15‰; however, the difference was not significant among salinities after 90 days of culture (p>0.05). All the prawn growth performance parameters significantly decreased with increasing salinities of 0, 5, 10 and 15‰ after 30, 60 and 90 day of culture (p0.05) and both were significantly higher than those at salinities of 10 and 15‰ (p < 0.05) after 90 days of culture. In addition, the survival rate reached 82.5–84.4% and did not insignificantly differ among alkalinities of 80, 100, 120, 140, and 160 mgCaCO₃ L⁻¹. However, the growth performance parameters and yield of AMGFPs at an alkalinity of 160 mgCaCO₃ L⁻¹ were significantly higher than those at lower alkalinities (80, 100, 120, and 140 mgCaCO₃ L⁻¹) after 90 days of culture. Therefore recommended that a salinity range of 0–5‰ and alkalinity of 160 mgCaCO₃ L⁻¹ is optimal for the growth-out culture of AMGFP juveniles.