 Antimicrobial peptides, amps, are found widely distributed throughout nature, and play an important role in the innate host defense of each species. In fish, amps include defensons, cathlosidons, hepsidons, histone-derived peptides, and a specific class of secretion family peptide known as pisidons. These peptides have broad spectrum antimicrobial activity against both fish and human pathogens, and can also modulate the immune system. Research has shown that certain properties of fish peptides, such as their ability to function in high salt concentrations, make them promising candidates for development into therapeutic antimicrobial agents. Additionally, the stimulation of their gene expression by external factors may be beneficial in preventing pathogenic microbes in aquaculture. This article was authored by Jorge Imasa Silva and Gil Diamond.