In this study, the acute toxicity of the heavy metal of cobalt on Cyprinus carpio was determined in the laboratory of the Science and Research Branch, Islamic Azad University, in 1384.
The experimental investigation took 96 hours using the O. E. C. D. guidelines. Fishes were divided randomly into eight groups of ten fishes each. The average length and weight of the fishes were 9±1.5cm and 10.125±2.19 gr, respectively. A group was chosen as the control group and seven groups were placed under concentrations of 50, 100, 200, 300, 400, 500, and 600 mg/Lit cobalt. All important physicochemical parameters of water including pH, dissolved oxygen, hardness, temperature, and conductivity, total alkalinity, phosphate, nitrate and nitrite were measured. All the examinations were done with two replicates. The data were analized using probit analysis with software spss. The 96h LC50 values of cobalt chloride for Cyprinus carpio with two replicates were values of 328 and 327 mg/Lit,. respectively.