Although P. salmonis co-infection modulated immune-related biomarkers in the head kidney, spleen, and liver (up-regulation of cytokines such as il-1β, ifnγ, il8, and il10; antimicrobial peptides such as hepdicin; PRRs such as tlr5s), increased pathological changes in fish (e.g., the formation of ascites, pale nodules in the liver, swollen kidney, and distended ventricle) and decreased survival rate compared to single-infected fish, the potential single-tank effect should be considered in further studies. Here, IL1B is linked to coinfection.