The objectives of the present study were to analyze the effect of temperature regimes on stress levels and to determine the suitable water temperature for the domestication of tapah, Wallago leeri Bleeker. A completely randomized method was used in this study, and three levels of water temperature were tested, namely, 27, 29, and 31°C, in seven replicates. A total of 500 experimental fish were collected from the Kampar River, Langgam, Riau, Indonesia, and transported to the Aquaculture Laboratory, Riau University. The fish were reared in 21 tanks at stocking densities of 70-100 fish tank−1. The fish were fed rough fish three times a day at 08:00, 12:00, and 21:00 for 30 days. Blood samples were taken on days 1, 14, and 29, which were analyzed for cortisol, glucose, and plasma protein. Growth and survival rates were recorded at the end of the experiment. ANOVA showed that water temperature had a significant effect on the stress condition, growth, and survival rate of tapah. Lower blood glucose, protein, and cortisol plasma levels were recorded in fish acclimatized at 29°C with values of 14.44 mg dL−1, 5.35 g dL−1, and 6.90 mg mL−1, respectively. Additionally, higher growth performance (32.30 g) and survival rates (100%) were also found in fish reared at 29°C. It was concluded that the best water temperature for the domestication of tapah is 29°C.