Abstract: Fishes are one of the organisms that have managed to survive in a milieu of pathogenic organisms. The primary interference of fish with their environment happens through a mucous layer that covers its entire body. Marine fishes possess antimicrobial peptides as a part of their defense system, which are mainly present in the mucous layer indicating that they eliminate the pathogenic bacteria before they enter the skin barrier. A number of α-helical Antimicrobial Peptides (AMP) such as Pardaxins, Misgurin, Pleurocidins, Parasin, Oncorhyncin II and III, Chrysophsin and HFIAP (Hagfish Intestinal Antimicrobial Peptide) have been isolated from different species of fishes. However, studies on the role of antimicrobial peptides in fishes are very limit. Various mechanisms developed by multicellular organisms in nonspecific immunity raises questions on the role of antibiotic peptide as a deterrent against infection. The present study provides a general introduction to the subject with special emphasis on the role of bioactive peptides in marine fishes.