Effects of different temperature levels on the opercular respiratory rate of Clarias anguillaris fingerlings were investigated for a period of 6 weeks under laboratory conditions. Fifty fingerlings were raised in water temperatures of control (26.66±0.28), 30.00, 32.00, 34.00 ⁰C with 2 replicates each respectively. Opercular Respiratory Rates (ORR), body weight, and physicochemical parameters were determined weekly based on standard methods.  ORR was significantly (p < 0.05) reduced from 113.60 ± 7.67 to 105.50 ±10.23 opercular beats per minute from week 1 to 2 in the control temperature. ORR was also significantly (p < 0.05) higher from 30 to 34 ⁰C from week 1 to 2. A strong negative correlation was observed between body weight and ORR from all the treatments. Electrical conductivity (519.92±5.06 to 586.33±17.50 µS/cm) and Ammonia concentration (1.11±0.10 to 1.98±0.06 mg/L) were (p < 0.05) higher from the control temperature to 30.00 ⁰C.  ORR of C. anguillaris fingerlings increased with an increase in temperature, while ORR decreased with an increase in fish size and duration of the experiment.  The temperature had no effects on dissolved oxygen, biochemical oxygen demand and pH except bodyweight in weeks 1, 3 and 5. Ammonia concentration and electrical conductivity increased with an increase in temperature. The findings from this study revealed that higher temperature levels affect the opercular respiratory rates, ammonia concentration, and electrical conductivity of Clarias anguillaris fingerlings in captivity.