White tail disease in Macrobrachium rosenbergii is emerging as a serious problem in the region. Two viruses, M. rosenbergii nodavirus (MrNA) and extra small virus (XSV) have been found to be associated. The role of MrNV and XSV is not yet clear. Considering the economic impact and potential for the disease to spread, white tail disease (MrNV and XSV) has been listed under non-OIE listed crustacean diseases relevant to the region and NACA/FAO/OIE Regional QAAD list.