A study on acute toxicity, oxygen consumption and behavioural changes in the three major Carps, Labeo rohita (ham), Catla catla (ham) and Cirrhinus mrigala (ham) exposed to Fenvalerate

Acute toxicity experiments for Fenvalerate technical grade and 20% EC formulation were conducted using static renewal bioassay and continuous flow through systems for 24h, 48h and 96 h on the three major carps, Labeo rohita, Catla catla and Cirrhinus mrigala. Although toxicity studies were conducted on both fry and fingerling stages, further experiments were carried out with fingerling stages only. After determining the LC50 concentrations for the three fish individually, one-tenth of the 24 h LC50 was taken as sublethal concentration for studies on oxygen consumption. The toxicant exposed fish showed anomalous behaviour like surfacing phenomenon, irregular, erratic and darting swimming movements, hyperexcitability, loss of equilibrium and hitting to the walls of the test tank before finally sinking to the bottom just before death. Oxygen consumption studies for a period of 12 hours, at intervals of 2 hours, in both sublethal and lethal concentrations indicated that lethal concentrations had profound effect than sublethal concentrations and 20% EC was found to be more deleterious than technical grade of fenvalerate. During experimentation, severe respiratory distress, rapid opercular movements leading to the higher amount of toxicant uptake, increased mucus secretion, higher ventilation volume, decrease in the oxygen uptake efficiency, laboured breathing and gulping of air at the surface were observed in all the three carps studied.