Study of the acute toxicity and behavioural responses of amur common carp (Cyprinus carpio haematopterus) exposed to varying concentrations of heavy metal (Zinc chloride)

Abstract

The present study evaluated the acute toxic effects and behavioural alterations induced by zinc chloride (ZnCl₂) in Amur common carp (Cyprinus carpio haematopterus) under controlled laboratory conditions. Healthy fish (length 4.3-6.5 cm; weight 3.12-6.34 g) were exposed to six different concentrations of zinc chloride (12 to 22 mg/L between) for a 96-hour period, along with a control group. Mortality data were analysed using the probit method to determine the median lethal concentration (LC₅₀). Water quality parameters were assessed using standard techniques during experiment and showed no significant variation, indicating stable experimental conditions. Result reveal that no mortality was recorded in the control group, whereas treated groups increase in mortality, ranging from 10% at 12 mg/L to 100% at 22 mg/L after 96 hours. Probit analysis revealed a strong linear relationship between log concentration and probit mortality (R² = 0.9054). The 96-hour LC₅₀ value of zinc chloride for Cyprinus carpio haematopterus was estimated to be approximately 16.12 mg/L, indicating moderate sensitivity of the species to zinc chloride exposure. The findings demonstrate that zinc chloride exerts acute toxic effects on Amur common carp, LC₅₀ value obtained in this study provides important baseline information for environmental risk assessment, water quality management and the regulation of zinc pollution in aquatic environments.