An iridovirus-like agent isolated from sheatfish Silurus glanis fry was used for infection trial. Sheatfish fry exposed to the water-borne virus exhibited anorexia, apathy, and ataxia. Mortality reached 100 % within 8 d at 25-degrees-C. Gross signs of the infection were petechial haemorrhages in the skin and internal organs. A generalized destruction of the haematopoietic tissues of spleen and kidney was prominent among infected fish. Virus particles were observed in the cytoplasm of endothelial, epithelial, and white blood cells in different organs. The virus could be reisolated from infected fish with infectivity titers of up to 8.2 log10 TCID50 ml-1.