Evaluation of lethal concentration (LC50) of zinc chloride (ZnCl2) and effects on behavioral responses of gray mullet (Mugil cephalus)

The aim of the present study was investigated the evaluation of the Median Lethal Concentration (LC50) Toxicity of Zinc Chloride (ZnCl2) and its effect on behavioral responses of gray mullet (Mugil cephalus). For this experiment, healthy of gray mullet with mean weight 7.42 g and mean length 6.51cm were captured from the Chabahar Bay. At the first, fish were exposed to ZnCl2 at several selected concentrations 0.25, 0.5, 1, 5, 10, 15, 20, 30, 40 ppm for rang finding test, then fish exposed to four concentrations 16, 17, 18 1nd 19 mg/L of Zncl2 for LC50-96h. Experiment was carried out in triplicate and 21 fish per each treatment. Physicochemical properties of water were measured continuously throughout the experiment. The temperature, pH, dissolved oxygen and salinity were 30 ◦C, 7.75, 8.25 mgO2 L-1 and 38 ppt respectively. Number of mortality and behavioral responses of fish were recorded after 24, 48, 72 and 96 h. The behavioral changes observed in fish at the experiment period included reversal, swimming on water surface, nervous manifestations, swallowing air, rapid opening and closing of the operculum, congestion and bleeding of mouth, gills and fish fins and slow down motility change of body coloration and increased of mucus secretion. LC50 of zinc chloride value was calculated with spss and probit analysis and was determined to be 17.33 mg/L in a static bioassay test system.