After perceiving stress, a primary stress response, i.e. increased circulating levels of catecholamines (CAT) and cortisol, is initiated through the hypothalamic-pituitary-interrenal axis. This elicits secondary stress responses, in fish documented as cellular, osmoregulatory, hematological, barrier or immunological changes. This may create tertiary stress responses, affecting performance and manifested as decreased growth, swimming capacity, disease resistance, feeding activity and altered behaviour