Atlantic Salmon (Salmo salar) Interleukin-8 (IL-8), a member of the CXC chemokine family, is a key pro-inflammatory mediator that regulates leukocyte recruitment and activation in teleost fish. Functionally analogous to mammalian IL-8, salmon IL-8 is rapidly induced in response to bacterial pathogens such as Aeromonas salmonicida and Vibrio species, viral infections including infectious salmon anemia virus (ISAV) and piscine orthoreovirus (PRV), and parasitic challenges such as sea lice (Lepeophtheirus salmonis). Expressed in immune-relevant tissues including gill, skin, spleen, kidney, and intestine, IL-8 promotes chemotaxis of neutrophil-like granulocytes and macrophages to sites of infection or tissue damage, supporting early innate immune defense. Elevated IL-8 expression is associated with localized inflammation and disease severity, making it a valuable biomarker for immune activation and pathogen exposure in aquaculture systems. In research and industry settings, characterization of Atlantic salmon IL-8 supports studies of mucosal immunity, vaccine efficacy, stress physiology, and host-pathogen interactions in aquatic environments, contributing to improved disease management, selective breeding for resistance, and sustainable aquaculture practices.