The search for safe, affordable, and environmentally friendly anaesthetic agents has intensified due to increasing concerns regarding the use of synthetic chemicals in aquaculture. This study evaluated the anaesthetic efficacy of aqueous crude leaf extract of Erythrophleum suaveolens on juvenile Clarias gariepinus, with particular emphasis on induction and recovery times, behavioural responses, survival, water quality, and haematological changes. Healthy juveniles of C. gariepinus were randomly assigned to six treatments consisting of a control (0.00 g L⁻¹) and five concentrations of aqueous crude leaf extract (2.00, 3.00, 4.00, 5.00, and 6.00 g L⁻¹). Fish were observed for behavioural responses, induction time, recovery time, and survival, while water quality parameters (dissolved oxygen, temperature, pH, and free carbon dioxide) and haematological indices were determined using standard laboratory procedures. Data were analysed using one-way analysis of variance (ANOVA) at a 5% level of significance.The results showed that dissolved oxygen and pH decreased significantly (P < 0.05) with increasing extract concentration, whereas free carbon dioxide increased significantly. Water temperature remained relatively stable and did not differ significantly (P > 0.05) among treatments. Induction time decreased progressively with increasing extract concentration, while recovery time increased from approximately 1 to 5 minutes. Behavioural responses, including reduced swimming activity, loss of equilibrium, and complete anaesthesia, were concentration dependent. The highest mortality (100%) was recorded at 2.00 g L⁻¹ under the experimental conditions because of prolonged induction time and extended exposure. Haematological analysis revealed significant changes (P < 0.05) in white blood cell count, mean corpuscular volume, and platelet distribution width, whereas red blood cell count, haemoglobin concentration, haematocrit, mean corpuscular haemoglobin concentration, platelet count, and mean platelet volume were not significantly affected.The study demonstrates that aqueous crude leaf extract of Erythrophleum suaveolens possesses anaesthetic properties capable of inducing anaesthesia in juvenile Clarias gariepinus. However, the observed mortality at lower concentrations indicates that careful optimisation of exposure time and dosage is necessary before practical application. Further studies involving phytochemical characterisation, toxicity evaluation, histopathological assessment, and residue analysis are recommended to establish the safety and suitability of the extract as a botanical anaesthetic for sustainable aquaculture.