TOXICITY EFFECTS OF FENITROTHION ON ESTERASE IN TILAPIA FISH (Oreochromis niloticus)
This study focused on toxicity effects of fenitrothion on esterase in tilapia fish (Oreochromis niloticus). Specific esterase activity, I 50 value and k i value of O. niloticus were determined. The optimum parameters for esterase activity in O. niloticus were at pH 7 of phosphate buffer, 12x10 -4 M of substrate concentration, at 25 ο C after incubated for 30 minutes. The specific esterase activity was 3.578x10 -7 µmol mg -1 min -1 . The I50 value for fenitrothion was found at 1x10 -4.315 M with the inhibition rate of 14.66. Fenitrothion caused moderate toxic to the population of fish