Fish Viruses

Leong, J.C.

Viral pathogens impact both wild and farmed fish. In some cases, outbreaks of these diseases in populations of fish can lead to the near extinction of a particular race of sockeye salmon or such severe losses as to put commercial aquaculture ventures out of business. The importance of fish viruses to the aquaculture industry has increased the number of reported new virus isolations and the host range of previously characterized viruses. Currently, the fish viruses are represented in 14 of the families listed for vertebrate viruses by the International Committee on the Taxonomy of Viruses. The fish viruses containing DNA genomes are listed in the families Iridoviridae, Adenoviridae, and Herpesvirdae and those with RNA genomes are listed in the families Picornaviridae, Birnaviridae, Reoviridae, Rhabdoviridae, Orthomyxoviridae, Paramyxoviridae, Caliciviridae, Togaviridae, Nodaviridae, Retroviridae, and Coronaviridae. Many of these viruses have grown optimally at the temperature of the host (8–15 °C). A few of the viruses can cross the species barrier and infect other fish species, cattle, pigs, and humans. As the need of aquacultured fish grows and the industry brings into culture more diverse species of fish, it is likely that there will be new virus isolations and some will be subsequently classified as new genera or even families.