A study on mortality of Common carp (Cyprinus carpio) and Caspian kutum (Rutilus frisii kutum) exposed to chlorinated disinfectant soloution (Sodium Hypochlorite)

Release of detergents via urban sewages into aquatic ecosystems can have adverse effects on aquatic life. In this study, the acute toxicity of NaOCl on Common carp (Cyprinus carpio) and Caspian kutum (Rutilus frisii kutum) with average weights of 16±1 g (mean ± SD) and 3.5±1 g, respectively, was investigated to determine 50% lethal concentration of the fish populations in 96 hours.
Experiments were carried out in a static base according to O.E.C.D standard method in 4 days (96 hours). After primal experiments to explore the lethal range, the main research was performed by selection of 5 final treatments (0, 15, 30, 60, 120 mg L-1) for Cyprinus carpio and 6 final treatments (0, 5, 10, 20, 40, 80 mg L-1) for Rutilus frisii kutum, each one with 3 repeats. Eventually according to the results obtained by probit analyses, amount of LC1, LC10, LC30, LC50, LC70, LC90 and LC99 were calculated in fishes during 24, 48, 72 and 96 hours.
Findings: In the present study, 100% of mortality of Caspian kutum in concentration of 80 mg L-1, happened only within the first hours they exposed to pollution. However, this process in Common carp in concentration of 120 mg L-1, happened after 30 hours passed from starting the experiment. The acute toxicity of Common carp and Caspian kutum were 39.48 and 23.77 mg L-1 respectively.
The present study showed that this washer is dangerous for fishes and also Rutilus frisii kutum is much more vulnerable to NaOCl in comparison with Cyprinus carpio.