The acute toxic effects (LC50) of the Halamid (Chloramine-T) and its maximum allowable concentration (M.A.C.) on Kutum fingerlings Rutilus frisii kutum Kamenskii, 1901 with mean body weight 0.9g were studied in summer 2008. We carried out five treatments with three replicates and one control using the static O.E.C.D method in 20 liter aquariums that each containing 10 individual. For each treatment, three replications were conducted. During the experiments, the relevant physical and chemical parameters of water during the experiments were measured including PH which was in the range 7.1-7.7 the average PH, was recorded 7.5, total hardness was measured to be >250 mg/l (CaCO3), dissolved oxygen (DO): 78% and temperature which was recorded as 240C. The results indicated that the lethal concentration (LC50 96h) and M.A.C. value for Halamid (Chloramine-T) 21.4mg/l and 2.14mg/l respectively and in this study were determined at 24, 48, 72 and 96 hours post exposure in the Caspian Sea Kutum. Our complete survey and investigation as soon as in Iranian journal were published.
