Pesticide is a synthetic chemical contaminating aquatic ecosystems as a potential toxic pollutant, is investigated in the present study. The impact of exposure of the freshwater fish Heteropneustes fossilis to two sub lethal concentrations (0.07mg/L and 0.14 mg/L) of deltamethrin a synthetic pyrethroid/ pesticide for 30 days on the physiological activities of endocrine glands Ultimobranchial gland , Na+/K+ ATPase, Ca2+ and Mg2+ ATPase and inorganic ions Na+, K+ , Caz+ and Mg2+ in brain, kidney, gills, muscle and intestine was assessed. Significant (p<0.01) decrease was found in Na+/K+ ATPase, Ca2+ and Mg2+ ATPase activities in fish exposed to higher concentration. Ionic levels in vitals tissues were significantly decreased after exposure to the two sub lethal concentrations. Ultimobranchial gland, Brain and intestine were found the most affected tissues.