Thermal tolerance and metabolic activity of yellowtail catfish Pangasius pangasius (Hamilton) advanced fingerlings with emphasis on their culture potential

Thermal tolerance and metabolic activity of Pangasius pangasius fingerlings (22.7 ± 1.5 g) was evaluated in terms of critical thermal maximum (CTmax), critical thermal minimum (CTmin), lethal thermal maximum (LTmax), lethal thermal minimum (LTmin) and rate of oxygen consumption after acclimating the fingerlings at 30, 34 and 38 °C for 30 days. CTmax (mean ± S.E.) (42.68 ± 0.03, 43.67 ± 0.05, 44.05 ± 0.12), CTmin (12.37 ± 0.03, 14.48 ± 0.03, 17.22 ± 0.09), LTmax (42.95 ± 0.02, 44.35 ± 0.02, 44.53 ± 0.03) and LTmin (11.75 ± 0.02, 12.52 ± 0.03, 14.35 ± 0.02) increased significantly (p < 0.05) with increasing acclimation temperatures. Oxygen consumption rate increased significantly (p < 0.05) with increasing acclimation temperature from 30 to 34 °C, but the change was not significant from 34 to 38 °C. Temperature quotient (Q10) of acclimated fish (2.47) was lesser than the non-acclimated fish (3.27). The area of thermal polygon over the range of acclimation temperatures (30–38 °C) of P. pangasius was calculated as 231 °C2. Overall results indicate that thermal tolerance and metabolic activity in P. pangasius is dependent on acclimation temperature and is comparable to Indian major carps, suggesting their culture potential in tropical region.