Residue Levels of a Sub Lethal Dose of Organochlorine Endosulfan in Whole Fish of Tilapia Species Oreochromis niloticus.

Residual analysis of a sub lethal dose (0.02mg/l) of the insecticide endosulfan was studied in Nile tilapia species (Oreochromis niloticus). The species showed an ability to accumulate both alpha and beta endosulfan reaching maximum after 48 hours’ exposure. Beyond which there was a steady elimination of the pesticide until reaching undetectable levels at day 7 for alpha endosulfan and day 9 for beta endosulfan. At day 11 none of the two isomers were detected. Results revealed higher levels of beta isomer relative to alpha isomer. Bioaccumulation Factor (BAF) of Total Endosulfan reached its maximum of 13,860 folds after 48 hours of exposure and minimum of 400 after seven days. At day 11 Endosulfan level was not detected. Following that BAF increased at day 13 to 11,420 folds and then decreased to 8,970 folds at day 15.