UTTAR PRADESH JOURNAL OF ZOOLOGY

Malathion (organophosphorus pesticide) is used worldwide in the agricultural field due to its biodegradability and non-persistent properties to control the harmful pest. However their range of harmful effects on animals extends far beyond the agricultural pest. The main objective of this study is to observe the impact of sub-lethal concentration (96 hours) of organophosphorus malathion on the gills of freshwater fish Clarias batrachus. The organophosphorus pesticide malathion (50% EC) was purchased from the local market of Jhansi. After volumetric experimentation and selection of required dose of biomarker (malathion) as per experimental protocol, value of malathion LC₅₀ 96 hours calculated 0.25 ppm. The sub-lethal concentration of 0.025 ppm was determined by using 1/10th of LC₅₀ at 96 hours. The effect of malathion on sub-lethal concentration (1/10 of 96 hours of LC₅₀) and histological observation were recorded on the gills of treated fishes. Some reasonable alterations were observed in the gills sections of treated fishes as compared to the control group. These histological changes were characterized as:- Thickening of secondary lamellae, hemorrhage at primary lamellae, deformation of the cartilage core, erosion of secondary lamellae, blood congestion in the secondary lamellae, shortening of the secondary lamellae. This study indicates that the deformation of the gills depended on the duration of exposure and concentration of Malathion dose.