Effect of cadmium on glycogen content in muscle, liver, gill and kidney tissues of freshwater fish Channa punctatus (Bloch)

Aquatic environment gets polluted by heavy metals because of their environmental persistence and ability to bioaccumulate in aquatic organisms. Cadmium is a ubiquitous toxic heavy metal, biologically non-essential element, it is not biodegradable and has a very long biological half-life. The aim of the present study was to assess the glycogen content in muscle, liver,  gill and kidney of Channa punctatus exposed to sublethal concentrations of cadmium chloride after 4, 7, 15 and 30 days of exposure. The results clearly showed significant decrease in the glycogen levels in the experimental fish C. punctatus. Decrease in muscle glycogen was found highly significant (P<0.001) after 30 days in both low concentration (36.823 mg/L) 6.12±0.41mg/g and in high concentration (73.646 mg/L) 4.04±0.32 mg/g in comparison to control. Decrease in liver glycogen content was found highly significant (P<0.001) after 30 days in high concentration 9.12±0.49 mg/g when compared with control. The decrease in gill glycogen content after 30 days exposure was found highly significant (P<0.001) 1.36±0.13 mg/g in low concentration and in high concentration 0.79±0.25 mg/g in comparison to control. Decrease in kidney glycogen content was found highly significant (P< 0.001) at 30 days in low concentration 3.92±0.05 mg/g  and in high concentration 2.81±0.20 mg/g  in comparison to control. The influence of toxicant cadmium chloride in selected tissues of fish was taken into account in evaluating fish response against stressor. Hence, we can use glycogen content as biomarker of cadmium stress in fish.