Abstract
Increasing fish farming density has led to significant challenges, such as the rapid spread of infectious diseases, including concurrent infections and immunosuppression, causing substantial economic losses, so vaccination is now recognized as a reliable and standardized method for protecting against these infectious agents. To address this need, polyvalent vaccines have taken the place of monovalent vaccines in aquaculture. Nonetheless, there is a divide among researchers, with some advocating for monovalent vaccines while others support polyvalent vaccines in aquaculture, presenting a significant challenge for the industry. The difference between monovalent and polyvalent vaccines lies in their target pathogens and scope of protection. Monovalent vaccines are designed to target a single pathogen and are very effective in preventing a specific disease. In contrast, polyvalent vaccines target multiple pathogens simultaneously, offering broader protection. While monovalent vaccines may require multiple injections to protect against several diseases, polyvalent vaccines simplify the vaccination process by combining protection in one injection, which reduces costs and lowers stress on the fish. Consequently, polyvalent vaccines provide a more efficient and comprehensive immunization solution for fish, especially in situations where concurrent infections are common. Given the challenges outlined, this article aims to compare the immunogenicity of monovalent and polyvalent bacterial vaccines administered via oral, immersion, and injection methods in aquaculture sector.