Viral diseases in Indian freshwater and marine water pisciculture

Intensification of aquaculture allows emergent and resurgent viral pathogens to cause large die-offs in the wild and farms. The inherent capability of viruses to exist in multiple forms outside the hosts gives them an edge for easy transmission and translocation increasing the chances of infection. More efforts are needed for an in-depth understanding of viral epidemiology. Quantification of factors determining the virulence mechanisms and variability in disease expression is necessary to strengthen the basic knowledge on viro­logy. The article is an update on the current understanding on viral diseases in fish causing loss to Indian aquaculture systems.