Unveiling the Impact of Key Major Fish Viruses on Aquaculture (a Review)

Aquaculture is the world's fastest-expanding industry, yet faces major challenges from aquatic diseases, especially viral infections. In recent years, aquatic diseases have had massive economic and environmental consequences, and the emergence of novel aquatic infections, particularly viruses, poses a constant threat. According to recent discoveries, fishes harbour more viruses than any other vertebrate class. Fish viruses encompass a wide array of pathogens belonging to diverse viral families such as the Reoviridae, Birnaviridae, Iridoviridae, and Rhabdoviridae. These viruses infect various fish species at different developmental stages, causing diseases ranging from mild to severe, often resulting in mass mortalities and substantial economic losses. Addressing viral diseases in aquatic species remains challenging due to the scarcity of effective therapeutics available, and the discovery of potent viral vaccines for delivery in aquatic systems remains a long way off. Research efforts focusing on understanding viral pathogenesis, host-virus interactions, and vaccine development are essential for mitigating the impact of fish viruses on aquaculture sustainability. Despite these challenges, there exists limited information on the diversity, abundance, and evolution of fish viruses. This review emphasizes the diversity of fish viruses, their transmission dynamics, and their profound implications for aquaculture and prevention with a keen focus on important fish species.