We used a panel of cellular, serological and molecular methods associated to in vivo experimental infections to characterize a virus isolated from sea bass larvae in winter 2018 in the context of an increase of mortality / morbidity in several batches of a hatchery. Here, sequencing of the extracted RNA from the batch 19/364-17 revealed the presence of not only the Toti-like virus which was shown to grow on fish cell line but also of more than 10 viruses such as dicistrovirus, rhabdovirus, ...