The energetic costs of being in stressful conditions require the involvement of hormones associated with metabolic support, which may also influence immune function. The present work aimed to explore the links between tryptophan nutrition and metabolic responses in European seabass (Dicentrarchus labrax) held under space-confined conditions, and subsequently submitted to an immune challenge. To study that, two dietary treatments were evaluated, i.e. control diet (CTRL) and CTRL-based diet supplemented with tryptophan (0.3%
TRP) to fish under space-confinement conditions (10 kg/m