ABSTRACT
Mancozeb, a broad-spectrum di thio carbamate fungicide, is widely applied in agriculture but poses significant ecotoxicological risks when introduced into aquatic ecosystems. This study investigates the acute toxicity, behavioural changes, and biochemical disruptions induced by Mancozeb in adult zebrafish (Danio rerio). Fish were exposed to concentrations of 1, 2, 3 mg/L for 72 hours. A concentration-dependent increase in mortality was observed, with 50% mortality recorded at (LC50) 1 mg/mL and, 60% of mortality at 2mg/L at 48 hours and LC100 recorded at highest concentration 3mg/L after 72 hours.
Behavioral assays including the novel tank diving, light-dark preference, and shoaling tests revealed reduced exploratory behavior, increased bottom-dwelling, heightened anxiety, and altered group cohesion in exposed groups. Biochemical analysis of liver tissue showed a marked reduction in hexokinase activity from 2.75 U/mg protein (control) to 1.05 U/mg at the highest concentration, and glucose-6-phosphatase activity is 8.2 U/mg to 2.92 U/mg declined significantly, indicating metabolic suppression. Protein levels in muscle tissue declined from 8.30 to 2.50 mg/g while glycogen content in gills reduced from 8.20 to 2.5 mg/g. while cholestrol content 8.45 to 3.19 mg/g after 72 hours. These findings confirm that Mancozeb induces acute biochemical and behavioural toxicity in zebrafish, even at sub-lethal concentrations, emphasizing its potential threat to aquatic biota and the necessity for stringent environmental monitoring