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Experiments on bioassay was undertaken to find the toxic effect of ‘Phorate 10G’ on survival of fingerlings of tilapia. Lethal concentration range of ‘Phorate 10G’ for tilapia fingerlings was observed to be 0.02 to 0.2 mgl-1. The 96 hrs LC50 of ‘Phorate 10G’ for fingerlings of tilapia was found to be at 0.034 mgl-1. Tilapias were exposed to the sublethal concentrations of 0.05 and 0.075 mgl-1 for a total period of 30 days. At the end of exposure periods of 10, 20 and 30 days, after every ten days, ten fingerlings were sacrificed for carcass biochemical composition such as moisture content, crude protein, and crude fat and total ash content. The moisture and total ash contents of the tilapia were increased, whereas crude protein and crude fat content decreased as a function of increased the concentration of ‘Phorate 10G’ and exposure period.
Keywords: Phorate 10G, Organophosphate, Tilapia sp., LC50, Sublethal exposure, Biochemical composition.