The most important emerging fish viruses, including tilapia lake virus, viral nervous necrosis, infectious pancreatic necrosis, viral encephalitis of tilapia larvae, Spring viremia of carp, Koi Herpesvirus. In this respect and to provide a better understanding of the variety of viruses that pose a threat for cultured fish species, topics such as epidemiology, global distribution, conventional and molecular methods of diagnosis are included. These elements provide a framework for advancing knowledge and guiding for long-term prevention strategies.