Five isolates of a rhabdovirus associated with a severe ulcerative disease of striped snakehead, Ophicephalus striatus, and other freshwater fish in S.E. Asia were examined for growth in a range of cold and warm water fish cell lines and for serological relationships to other pathogenic fish rhabdoviruses. All five isolates grew in AS, BF-2, snakehead, O. striatus and O. micropeltis, and climbing perch, Anabas testudineus, cell lines. CHSE-214, RTG-2, EPC, Nile tilapia, Oreochromis niloticus, and grass carp Ctenopharyngodon idella, cell lines were all refractory to infection. Cross neutralization tests showed the ulcerative disease rhabdovirus (UDRV) to be serologically distinct from VHSV, IHNV, EVA, EVX, SVCV, PFRV and perch rhabdovirus. UDRV appears to be a new distinct pathogen of freshwater fish in S.E. Asia.