Toxicity Evaluation and Mortality Responses of Pangasius hypophthalmus During Experimental Exposure to Some Agricultural Pesticides

3 Abstract: The aim of the present study was to investigate acute effects of diazinon and deltamethrin as potential dangerous agricultural chemicals to assess and compare mortality rates of these chemicals on Tra catfish (Pangasius hypophthalmus) in the form of LC . Fish samples (7 fish in each test group) were exposed 50 to different concentrations of diazinon and deltamethrin (between 0-40 ppm for diazinon and 0-2 ppm for deltamethrin) for 96 h in 120 L glass aquaria. Although significant difference was observed between acute toxicity of two chemicals, the very low LC obtained for deltamethrin (0.10 ppm) and diazinon (11ppm) indicated 50 that deltamethrin and diazinon are highly toxic to P. hypophthalmus. Further studies are recommended to investigate the effects of these chemicals on the physiological and histological impacts and their accumulation in vital tissues of fishes. Although these chemicals are thought to be less toxic in field conditions due to their adsorption to sediments, these data are useful when assessing potential ecosystem risks.