Acute Toxicity of Bispyribac Sodium on the Survival of African Catfish (Clarias gariepinus) Juveniles and its Implications for Food Safety

Background and Objective: The increasing use of Bispyribac sodium in agriculture raises concerns about its potential toxicity to non-target aquatic species. However, information on its acute effects on Clarias gariepinus juveniles, a widely cultured food fish, remains limited. This study assessed the acute toxicity of Bispyribac sodium to C. gariepinus juveniles and examined associated changes in water physicochemical parameters. Materials and Methods: Juvenile C. gariepinus were exposed for 96 hrs to five concentrations of Bispyribac sodium (0.59, 0.88, 1.31, 1.97, and 2.95 mg/L) and a control (0.00 mg/L). Each treatment contained ten fish in replicated 70-L bowls filled with 20 L of water. Mortality was recorded upon cessation of gill movement and lack of response to gentle prodding. Water quality parameters (pH, dissolved oxygen, temperature, electrical conductivity, and total dissolved solids) were measured using a HANNA multiparameter meter. Mortality data were analyzed to estimate the 96 hrs LC₅₀ using probit analysis, with treatment effects assessed by one-way ANOVA followed by Dunnett’s test (α = 0.05), and all analyses were conducted in SPSS v25. Results: Mortality increased with concentration, ranging from 20% at 0.59 mg/L to 75% at 2.95 mg/L, with no mortality in the control. The 96 hrs LC₅₀ was 1.658 mg/L (95% CI: 1.204-2.289 mg/L), indicating a strong dose-dependent relationship (Probit = 2.1874×LogC+4.5189, R² = 0.9552). Significant changes (p<0.05) occurred in pH (6.15-8.05), TDS (327.0-358.0 mg/L), EC (654.0-716.0 μS/cm), and DO (5.60-2.75 mg/L), while temperature remained stable. Fish at higher concentrations exhibited restlessness, weakness, and edge-settling behavior. Conclusion: Bispyribac sodium demonstrated considerable acute toxicity to C. gariepinus juveniles and induced notable alterations in water quality parameters. The species’ sensitivity suggests its suitability as a bioindicator of herbicide contamination. Careful regulation of Bispyribac sodium is recommended to minimize risks to aquatic health and food safety. Further studies are needed to refine safety thresholds for aquaculture environments.