Antimicrobial peptides (AMPs) are the vital constituents that stimulate the
innate immune defense system against pathogens and perform several biological
activities, which provide the first defensive line against infectious diseases. Owing to
their unique structure, they can be utilized as a therapeutic strategy for infectious
diseases in fishes. Several kinds of AMPs are reported in fishes with broad-spectrum
antimicrobial properties. Besides, the bacterial cells cannot develop resistance strains
against these cationic compounds with low molecular weight. Thus, AMPs may be
considered an alternative to antibiotics to prevent or control infectious diseases in
aquaculture. It is essential to provide sufficient knowledge about the mode of action of
AMPs against fish pathogenic agents and their future applications.