Viromics Reveals the High Diversity of Viruses from Fishes of the Tibet Highland.

Aquaculture is important for food security and nutrition. The economy has recently been significantly threatened and the risk of zoonoses significantly increased by aquatic diseases, and the ongoing introduction of new aquatic pathogens, particularly viruses, continues to represent a hazard. Yet, our knowledge of the diversity and abundance of fish viruses is still limited. Here, we conducted a metagenomic survey of different species of healthy fishes caught in the Lhasa River, Tibet, China, and sampled intestinal contents, gills, and tissues. To be more precise, by identifying and analyzing viral genomes, we aim to determine the abundance, diversity, and evolutionary relationships of viruses in fish with other potential hosts. Our analysis identified 28 potentially novel viruses, 22 of which may be associated with vertebrates, across seven viral families. During our research, we found several new strains of viruses in fish, including papillomavirus, hepadnavirus, and hepevirus. Additionally, we discovered two viral families, Circoviridae and Parvoviridae, which were prevalent and closely related to viruses that infect mammals. These findings further expand our understanding of highland fish viruses and highlight the emerging view that fish harbor large, unknown viruses. IMPORTANCE The economy and zoonoses have recently been significantly threatened by aquatic diseases. Yet, our knowledge of the diversity and abundance of fish viruses is still limited. We identified the wide genetic diversity of viruses that these fish were harboring. Since there are currently few studies on the virome of fish living in the Tibet highland, our research adds to the body of knowledge. This discovery lays the groundwork for future studies on the virome of fish species and other highland animals, preserving the ecological equilibrium on the plateau.