Determining the Lethal Concentration of Formalin to Koi fish (Cyprinus carpio)

Formalin is a chemical disinfectant for surface and premises beside its effect on several infective pathogens in ornamental and food fishes. Determination of formalin concentration for precious fish is critical. This problem is so important because of the aquarium fish varieties. In this study, OECD standard method was used for Koi fish formalin LC50 assessment. After a series of basic experiments, seven logarithmic concentrations plus a control group in three repeats were determined. Mortality were recorded per day and by using “Probit analysis”, LC10, LC50 and LC90 were calculated after 96 hrs, e.g.,148.93, 172.81 and 200.52 mg.L-1 respectively. MAC, MIC and NOEC were estimated 17.28, 148.39 and 17.28 mg.L-1 in turn for Koi.