ABSTRACT: Fish actively select an adequate environment that fits their optimum culture/preferred temperature, this mechanism is called thermoregulatory behavior. However, what exactly is this mechanism, how does it work and what can we learn from it? Helped by their thermal limits, fish avoid temperature variations not favorable for their maximum growth. They find a thermal window where optimal temperature culture is located and use it in the best way possible for all activities. The present study is based on thermal biology studies, and its purpose is to learn the aerobic scope functions on Pargo-UNAM juveniles. The importance of this study is related to the fact that Pargo-UNAM fish, being a hybrid, has five different genetic backgrounds. We found that acclimation temperature influenced the preferred temperature of Pargo-UNAM, having a metabolic adjustment in the 20-32ºC range; the Final preferendum obtained was 29.5ºC. The maximum and minimum range of critical thermal limits was between 39.2-43.5ºC and 8-14.9ºC, respectively. The thermal window had an area of 355.2ºC2. The acclimation response ratio had a 0.40-0.35 interval for CTMax, and 0.52-0.69 for CTmin. Chase method used in Pargo-UNAM caused a maximum aerobic scope at 29ºC. Blood lactate concentration was the highest in fish acclimated at 20ºC; these values decreased while acclimation temperature increased. Results from Pargo-UNAM juveniles showed that these can be grown successfully in a 26-32ºC temperature range, with their greater performance at 29ºC, where the aerobic scope was at its maximum capacity.