Physiological and metabolic responses of Nile tilapia (Oreochromis niloticus) fry to dietary substitution of fish meal with Ulva sp.

This study investigated the physiological and metabolic responses of Nile tilapia (Oreochromis niloticus) fry to dietary substitution of fish meal with Ulva spp. over a 60-day feeding period. Fry were fed four isonitrogenous diets (40% crude protein) containing 0%, 5%, 10%, and 15% Ulva spp. Physiological assessments included antioxidant enzyme activities superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) along with hematological parameters such as hemoglobin concentration, red blood cell (RBC) count, white blood cell (WBC) count, and hematocrit value. Dietary inclusion of Ulva spp., particularly at 5%, significantly enhanced antioxidant enzyme activities and improved hematological indices compared to the control group (P