Exploring the potential of seaweed Gracilaria gracilis and microalga Nannochloropsis oceanica, single or blended, as natural dietary ingredients for European seabass Dicentrarchus labrax

Gracilaria gracilis and Nannochloropsis oceanica , single or blended, were tested in European seabass ( Dicentrarchus labrax ) diets. A control (CTRL) diet was compared with experimental diets including either 8% G. gracilis (GRA8), 8% N. oceanica (NAN8), or a blend of 4% of each alga (NAN4GRA4). After 106 days of feeding, growth, nutrient utilization, antioxidant defense, immunological status, and end-product quality were evaluated. All fish exhibited similar feed intake (1.4–1.5%), body weight, growth, and feed conversion ratio (1.6). Dietary inclusion N. oceanica did not affect digestible N intake and gain. Fish fed GRA8 had the lowest digestible N and energy intake ( P