Acute toxicity test and safety evaluation of eight aquaculture pharmaceuticals in Hippocampus abdominalis juveniles

Objective The study aims to determine the safe concentrations of eight commonly used aquaculture pharmaceuticals (trichloroisocyanuric acid, formaldehyde, copper sulfate, hydrogen peroxide, zinc sulfate, metalaxyl, benzalkonium bromide, and niclosamide) for Hippocampus abdominalis, providing theoretical guidance for breeding, medication practices, and disease prevention in H. abdominalis aquaculture.

Methods Under water temperatures of 16~18 ℃, juvenile H. abdominalis average body length: 4~6 cm; average body mass: (1.83±0.26) g were exposed to these pharmaceuticals using a semi-static water renewal and drug replenishment method.

Results The acute toxicity and toxic accumulation characteristics were analyzed through the toxic accumulation coefficient (TAC). Results showed the safe concentrations (from highest to lowest) were: formaldehyde (24.858 mg/L), hydrogen peroxide (19.489 mg/L), trichloroisocyanuric acid (1.481 mg/L), metalaxyl (0.399 mg/L), copper sulfate (0.339 mg/L), benzalkonium bromide (0.242 mg/L), zinc sulfate (0.185 mg/L), and niclosamide (0.024 mg/L).

Conclusion All eight pharmaceuticals exhibited positive TAC values, indicating stronger cumulative toxicity than detoxification effects. Toxicity classifications were: low toxicity for trichloroisocyanuric acid, formaldehyde, and hydrogen peroxide; moderate toxicity for copper sulfate, zinc sulfate, and metalaxyl; and high toxicity for niclosamide.