Impact of cadmium toxicity on behavioral and haematological biomarkers of freshwater fish, Catla catla

Abstract

The present work is aimed to evaluate LC 50 values of Cadmium chloride for freshwater and common people edible fish, Catla catla , as well as to observe behavioural alterations treated with Cadmium. The LC 50 values for 24h, 48h, 72h and 96h were found 14.59, 10.76, 8.45 and 5.36 mg/l, respectively. The major behavioural alterations observed during the experiments were erratic swimming, S-jerk movements and burst swimming, restlessness, muscle spasm, fin flickering, profuse mucous secretion, discolouration of the integument in exposed animals. Overall increase in opercular beats in exposed fishes was also recorded throughout the experiments. The above modulations are considered as good bio-markers to access the health status of these valuable and cherished fishes as well as worsening status of aquatic bodies in relation to metallic contaminants, particular Cadmium. Haematological indices are considered to be pathophysiological indicators of the whole body and therefore are important in diagnosing the structural and functional status of animals exposed to pollutants. Exposure of fish to sublethal concentration of cadmium showed a significant decrease in the haemoglobin (Hb) content, total red blood cells (TRBC) and packed cell volume (PCV/Hct) at the end of 30 th day as compared to control, this may impair oxygen supply to various tissues, thus resulting in a slow metabolic rate and low energy production and indicates the worsening of an organism state and developing anaemia. Whereas the total white blood cells (TWBC) increased significantly, with increase in exposure periods, may be attributed to immunological response of the fish to heavy metal. To safeguard these, it is suggested, that the cadmium levels should be monitored and be restricted to release in to the aquatic environment either in any way with heavy metals monitoring devices.