Tilapia are considered to be relatively resistant to many of the common diseases that beset other farmed fish. Viral diseases, however, are not common, and there are only a few reports in the literature. Syncytial Hepatitis of Tilapia (SHT) is a newly described viral disease reported from several countries where tilapia farming is present. This virus is a member of the Orthomyxoviridae family. It has been demonstrated within hepatocytes of affected fish. The described ultrastructural changes provide further evidence to support the previous suggestion of...