Abstract: Serious economic losses in the aquaculture industry have been resulted from viral diseases in China as well as the worldwide. Mandarin fish Siniperca chuatsi is a special aquaculture fish in China. Siniperca chuatsi spheriacal virus (SCSV) has been demonstrated to be pathogen by a series of experiments such as electron microscope observation, cell challenge, host fish infection and histopathological investigation.However,the epizootic disease of mandarin fish could not be efficiently controlled by the viral vaccine. Different kinds of viruses were observed from the tissues of diseased mandarin fish with outbreak of infection and acute lethality. This study reveals two kinds viruses, Siniperca chuatsi spherical virus(SCSV) and Siniperca chuatsi rhabdovirus (SCRV) from diseased mandarin fish coinfected in vitro. The samples of viruses were prepared from tissues of the diseased mandarin fish with typical hemorrhage syndrome.The fish cell line of grass carp fins (GCF) was used to amplify the viruses.The infected GCF cells were collected at different time after infection, and the ultra thin section were cut, stained and examined by transmission electron microscopy. Two kinds of different viruses were observed, one is spherical virus and other is rhabdovirus. The morphogenesis ,coinfections and cellular interactions with GCF cells were investigated, such as the virus amplification in cytoplasm of infected cells,budding from the plasma membranes,and damages of the cells.These results may help explain the fact that different virus species are responsible for significant disease problems and pathogenesis in cultured fishes.