Assessment of acute toxicity and histopathology of the fungicide captan in rainbow trout

Acute toxicity of the fungicide, captan, to juvenile rainbow trout was evaluated under static-renewal test condition. Actual concentrations of captan ranged from 0.05 to 1.00 mg/L. The concentrations of captan that killed 50% of the rainbow trout (3.11 ± 0.8 g) within 24 (24 h; LC₅₀), 48, 72 and 96 h were 0.57 ± 0.09, 0.49 ± 0.10, 0.44 ± 0.11 and 0.38 ± 0.13 mg/L (95% confidence limits), respectively. None of the unexposed control fish died and the first fish died 6 h after exposure to captan (≥0.65 mg/L). Hypertrophy, separation of epithelium from lamellae, lamellar fusion, and epithelial cell necrosis were observed on captan exposed fish. Gills also had scattered areas of focal lamellar hyperplasia. Fish exposed to fungicide had inflammation and necrosis in liver, trunk kidney and spleen. In order, the most affected organs were gill, trunk kidney and liver.