Teleost fish possess an adaptive immune system that responds to various mucosal surfaces throughout their bodies. Research into mucosal vaccination and infection has shown that specific immune responses are triggered at different mucosal sites in teleosts. The primary mucosa-associated lymphoid tissues (MALT) in these fish include the gut-associated lymphoid tissue (GALT), skin-associated lymphoid tissue (SALT), gill-associated lymphoid tissue (GIALT), and the recently identified nasopharynx-associated lymphoid tissue (NALT). In recent years, there has been increased interest in developing mucosal vaccines for finfish to prolong protective immunity. Despite this, injectable vaccines continue to dominate as the preferred method for finfish vaccination, largely due to their perceived superior protection compared to mucosal vaccines.