Toxicological and behavioural study of mancozeb (fungicide) on zebrafish (Danio rerio)

The study evaluated the acute behavioral and structural toxicity of Mancozeb in adult zebrafish (Danio rerio). Fish were exposed to 0 (control), 1, 2, and 3 mg/L for 72 hours, and eight behavioral assays were performed. Mirror-biting frequency decreased from 12 counts/min in control to 9, 6, and 3 at 1, 2, and 3 mg/L, respectively, while the aggression index declined from 0.89 to 0.72, 0.51, and 0. Behavioral anxiety increased, with light-dark preference showing 21% time in dark zones for control and 46%, 63%, and 79% at 1, 2, and 3 mg/L, respectively. Shoal cohesion was reduced, with average inter-fish distance rising from 1.2 cm in controls to 2.8 cm at 3 mg/L. Startle response latency increased from 0.43 s in controls to 1.12 s at 3 mg/L, while predator response escape distance declined from 14.2 cm (control) to 5.1 cm at 3 mg/L. Structural analysis revealed a progressive severity index of 0 (control), 7 (1 mg/L), 13 (2 mg/L), and 19 (3 mg/L), characterized by fin erosion, skin ulceration, hepatic disintegration, gill necrosis, and collapsed swim bladder. These results demonstrated that Mancozeb exposure caused dose-dependent neurobehavioral deficits and organ damage in zebrafish, raising ecological concerns regarding its use in aquatic environments.