Temperature is one of the most dominant environmental factor influencing the biology and performance of aquatic ectotherms in the wild and in culture conditions. Thus, the aims of the present study were to investigate thermoregulatory behavior, thermal tolerance and active metabolic scope in Macrobrachium tenellum. To fulfill our goal, we measure, the preferred temperature, critical threshold limits, thermal window width, oxygen consumption routine rate and active metabolic scope in the prawn M. tenellum acclimated to 20, 23, 26, 29 and 32°C. The preferred temperature obtained by the graphic acute method was 28.5°C. Acclimation temperature significantly affected the thermal tolerance which increased with the acclimation temperature. The scope for thermal tolerance had an interval of 25.3 to 27.7°C. The thermal window calculated for M. tenellum was 325°C2 . The acclimation response ratios had an interval of 0.42-0.50. These values allow us to characterize these species as inhabitants of subtropical and tropical regions. The oxygen consumption routine rates increased as the acclimation temperature increased from 20 to 32°C. The range of temperature coefficient (Q10) between 29-32°C was the lowest, at 1.98. The active metabolic scope for prawns was the lowest for organisms acclimated to 20 and 32°C and the highest value was obtained at 29°C. The results obtained in the present study are important to determine the optimum conditions in which M. tenellum needs to live in the natural environment and may partially explain their wide distribution pattern along the Mexican Pacific Ocean littoral.