Effects of Seed Extract of Croton officinalis (Alston) on the Antioxidant Status of Oreochromis mossambicus (Peters)

A number of plant products have been used as fish poisons from time immemorial since they are readily available and economical. Freshwater fish, Oreochromis mossambicus, were exposed to different concentrations of the fish poison, seeds of Croton officinalis, for 96 hours. The LC value for 96-hour exposure to toxin was found to be 1.18 ppm. A comparative investigation of the effect of toxin at different sub-lethal concentrations on activities of antioxidant enzymes Catalase, Superoxide dismutase, Glutathione peroxidase, Glutathione-S-Transferase, and on lipid peroxidation in gills, liver, heart, kidney, and muscle tissues were carried out. The antioxidant enzymes significantly increased at lower doses, 0.13 ppm and 0.25 ppm and thereby enabled the organism to overcome the oxidative stress induced by toxin. On exposure to 0.42 ppm of toxin, the levels of malondialdehyde, conjugated dienes, and hydroperoxides significantly increased with the corresponding decrease of antioxidant enzymes suggesting that a severe antioxidant stress was experienced by fish exposed to higher concentration of toxin.