The purpose of this study was to determine the lethal toxicity and effect of fipronil on oxygen consumption rate, ammonia excretion rate and O:N ratio of Mahseer fry. The bioassay test was performed by adopting static renewal method. Results showed that the median lethal concentration (LC50) of fipronil for 96 hrs was 64.6 mgL-1 at 28±2°C. One tenth (6.46 mgL-1) and one fifth (12.92 mgL-1) of LC50 values was selected for sublethal studies. The rate of   oxygen consumption, ammonia excretion and O:N ratio was examined under two sublethal concentrations (6.46 mgL-1 and 12.92 mgL-1) of fipronil at 7 days intervals for 28 days. The results obtained in this study proposed that measurements of oxygen consumption rate, ammonia excretion and O:N ratio  can be useful indicators of stress .

Reference