Abstract
Megalocytivirus is a newly discovered DNA‐virus from the Iridoviridae family that possesses icosahedral symmetry and has a size range of 140–200 nm diameter. Based on genetic differences, Megalocytivirus is divided into three major groups; infectious spleen and kidney necrosis virus which is reported to cause disease in numerous marine and freshwater fish species, red sea bream iridovirus that mainly infects red sea bream [ Pagrus major (Temminck & Schlegel 1843)] and turbot reddish body iridovirus that is reported to infect Asian flounder species. Megalocytivirus has not been studied as extensively as other genera in the Iridoviridae family until recently; these viruses have received the most attention in research due to the wider host range and cause significant mortality and economic losses in the aquaculture industry. This review provides information on taxonomy, viral properties, epizootic, pathology and diagnostics of Megalocytivirus infection in fish.