The study investigates the influence of photoperiod (light-dark cycles) on the immune responses of the freshwater fish Channa punctatus. The findings demonstrate that variations in photoperiod significantly affect innate immune functions, including phagocytic activity and lymphocyte proliferation, with notable responses observed in key immune organs such as the head kidney and spleen. The study highlights the adaptive role of environmental light conditions in modulating fish immunity. This work contributes to a better understanding of environmental regulation of immune function and holds relevance for aquaculture and fish health management.