Atlantic Salmon (Salmo salar) Interleukin-4/13 (IL-4/13)–like cytokines are type 2–associated immune mediators that share functional homology with mammalian IL-4 and IL-13 and play important roles in regulating humoral immunity, macrophage polarization, and mucosal inflammatory responses in teleost fish. Due to genome duplication events in salmonids, Atlantic salmon possess multiple IL-4/13–like paralogs that signal through receptor complexes homologous to IL-4Rα/IL-13R–type chains, activating STAT6-dependent pathways that promote alternative (M2-like) macrophage activation, modulation of pro-inflammatory cytokine production, and support of epithelial barrier function. In salmon health, IL-4/13–like cytokines are particularly relevant in responses to parasitic infections such as Lepeophtheirus salmonis (sea lice), as well as bacterial pathogens like Aeromonas salmonicida and Piscirickettsia salmonis, where balanced type 2 responses contribute to tissue repair and regulation of excessive inflammation. Dysregulated expression may influence susceptibility to chronic inflammation or impaired pathogen clearance. As biomarkers of type 2–like immune polarization, Atlantic salmon IL-4/13–like cytokines are important in vaccine development, aquaculture disease management, and studies of host–pathogen interactions. Characterization of these cytokines supports comparative immunology research into the evolution of Th2-type immunity and informs strategies to enhance disease resistance and fish welfare in commercial aquaculture systems.