Acute toxicity, behavioural responses, and serum biochemical alterations in juvenile African catfish (Clarias gariepinus) exposed to African oil bean (Pentaclethra macrophylla Benth.) seed powder

Abstract

Plant-derived materials used in food processing may enter freshwater systems and expose non-target aquatic organisms to complex mixtures of bioactive constituents. This study determined the acute toxicity of African oil bean seed powder and evaluated associated behavioural and serum biochemical responses in juvenile African catfish. A 96-hour static, non-renewal bioassay was conducted using six nominal concentrations (0.00, 0.42, 0.50, 0.60, 0.70, and 0.80 mg/L), each in duplicate, with ten fish in 30 L of unchlorinated water per tank. Mortality and visible behavioural responses were monitored throughout exposure. At 96 hours, blood from three fish per tank was pooled, allowed to clot, and the serum was analysed for creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total protein, and cholesterol. Regression of probit response against log10 concentration yielded an estimated 96-hour median lethal concentration (LC₅₀) of 0.756 mg/L. Creatinine generally declined across the exposure series and differed significantly from the control at 0.60-0.80 mg/L. AST activity increased markedly at 0.70 and 0.80 mg/L, whereas ALT and cholesterol did not differ significantly among treatments. Total protein showed a variable, non-monotonic response. Body colouration changes, air gulping, erratic swimming, altered barbel condition, and loss of reflex became more evident with increasing concentration and exposure duration. The combined mortality, behavioural, and biochemical findings show that unprocessed African oil bean seed powder can induce acute biological stress in juvenile African catfish under static laboratory exposure. The study provides baseline evidence for further characterisation of the aquatic effects of African oil bean processing residues.