ABSTRACT                The African catfish (Clarias gariepinus) is a highly valuable species for aquaculture; it is extensively practiced in many countries across the world, involving Egypt. Therefore, the study aimed to investigate the potential effects of vitamin K (VK) on growth performance, haemato-chemical parameters, immune indices and antioxidant capacity. Four diets, each containing 30% crude protein, were formulated with 0.0% (control), 3mg kg^–1 diet, 6mg kg^–1 diet, and 9mg kg^–1 diet of VK. These diets were fed to the African catfish with an initial weight of 77.64 ± 4.89g ad libitum, three times daily, for 90 days. The fish were fed the experimental diet at 3% of their biomass daily. The results show that supplemental VK improves growth performance, feed utilization, immune responses, total protein, albumin, hemoglobin, and red blood cell count compared to the control. This study suggests that the optimal dietary VK level is 9mg VK kg^–1 diet due to its role in supporting growth, physiological functions, immune responses, welfare, and sustainability in the catfish diet industry.