Safety and toxicity evaluation of bronopol in striped catfish (Pangasianodon hypophthalmus)

Abstract

The study was performed to evaluate the safety and toxicity of bronopol in striped catfish Pangasianodon hypophthalmus. Bronopol product is licensed in Thailand and Vietnam for control of aquatic fungi and ciliated protozoa in scaleless fish at the daily dosage of 10 mg/l, 2-hour static immersion, for 5 consecutive days. Safe concentrations were evaluated in fish exposed to bronopol at the therapeutic dosage (10 mg/l, 2 hours, 5 consecutive days) and 2 and 3 times overdose (20 and 30 mg/l, 2 hours, 5 consecutive days). Fish treated with 10-30 mg/l bronopol for 2 hours daily for 5 consecutive days appeared clinically healthy and no adverse effects were found throughout the test period and for 30 days post treatment. These results show that the concentrations of bronopol of up to 3 times the therapeutic concentration are safe at 2-hour exposure. 24-hour median lethal concentrations tested in 3.5 g (SD ± 0.6) and 6.7 g (SD ± 1.2) fish were 11.04 and 11.18 mg/l, respectively, indicating that continuous immersion at the therapeutic dose can induce toxic effects. Therefore, bronopol is safe for use on striped catfish when it is administered at the therapeutic dosage.