Acute toxicity of nitrofurazone to channel catfish, Ictalurus punctatus, and goldfish, Carassius auratus

Acute toxicity tests with nitrofurazone yielded LC50 values of 84 mg per litre (4 h exposure)-19 mg per litre (48 h exposure) in channel catfish, and 178 mg per litre (7 h exposure)-71 mg per litre (96 h exposure) in goldfish. The 48 h LC01 values were 13.5 and 48.4 mg per litre in channel catfish and goldfish respectively. Skin and muscle lesions were observed in channel catfish. Epidermal inflammation was evident after 48 h exposure to 17 mg nitrofurazone per litre. This was followed by focal epidermal necrosis (eroded epidermis was 1-3 cells thick and covered with a thick layer of mucus), oedema in the underlying musculature, and enlargement of muscle cell nuclei. Skin lesions were not apparent in goldfish. The channel catfish experiments were conducted at low dissolved oxygen concentrations (2 mg per litre) to simulate conditions frequently encountered in channel catfish culture. Minimal dissolved oxygen concentration in goldfish experiments was 7 mg per litre.