The present study was undertaken to investigate the stability of a diazinon insecticide formulation (diazinon 60 % active ingredient EC) under different storage conditions at the temperatures 25°C, 54°C and sunny place for 14 days, and 72°C for 3 days, the persistence of active ingredient % of used insecticides was affected by storage condition and periods. The storage at room temperature for 14 days is not affected while storage at 72 GC was the most effective in the chemical decomposition., with the residue analysis of diazinon insecticide in liver , gills and muscle flesh of fish at acute toxicity with IhLCSO (2.99 ppm) after 3,5, and 7days of treatment, and with chronic toxicity treatment at 1/10 LCSO (0.6 ppm ) with air & without air in the aquaria after 7,14,21,28,35, and 42 days of treatments.