Effect of Agricultural pesticide (Cypermethrine) on Labeo rohita

Abstract

The effect of cypermethrine pesticide on juvenile rohu (Labeo rohita) was determined in captive condition in the fish physiology laboratory of Fisheries and Marine Resource Technology Discipline of Khulna University from September 15 to October 20, 2009. Live and healthy Rohu were exposed to five concentrations of Cypermethrine 0.625, 0.125, 0.025, 0.005, 0.001 ppm and a control group (no pesticide) with two replications for each treatment. The mean tank water temperature and pH of water in the experiment tanks were 21.53±〖0.41〗^∘ C and 7.22±0.13 respectively. The average initial body weight of the experimental Rohu was 20.965 g, 21.4 g, 20.55 g and 16.25 g in the control, 0.001 ppm, 0.005 ppm, and 0.025 ppm concentration tank respectively. The highest growth was recorded in control tank 0.2 g per week, whereas no significant growth was found in 0.001 ppm and 0.005 ppm concentration. Rohu reared in the 0.125 ppm had the lowest growth. The percentage of mortality of the test animals was varied depending on the concentration of pesticide and exposure time. The median lethal concentration values were found at 0.025, 0.005, 0.001, ppm for 9th, 17th, and 20th day respectively. Behavioral patterns were observed in both lethal (0.625, 0.125 ppm) and sub lethal concentration (.025 ppm). L. rohita in toxic media exhibited erratic and darting movements with imbalanced swimming activity, which might be due to the malfunctioning of neurotransmitters, followed by hyper and hypo opercula activity, loss of equilibrium, and mucus secretion all over the body were observed. The structure of the gill lamellae broken and colure of the gill turn into brown. Kidney in the dead fish was damaged and found some jellylike substance.