show Abstracthide AbstractMycobacteriosis caused by Mycobacterium spp. makes economic damages to the world aquaculture industry. In particurarily, Mycolicibacterium fortuitum, Mycolicibacterium salmoniphilum, Mycobacteroides chelonae and Mycobacterium marinum are major pathogens of Mycobacteriosis in cultured fish. In this project, we isolated novel Mycolicibacterium spp. from diseased koi carp Cyprinus carpio in Japan and clarified whole genome sequence of this species. The Mycolicibacterium spp. grow for 5 days on ogawa-medium at 30 degree with white color and smooth colony. In phylogenetic tree analysis, the Mycolicibacterium spp. belonged to Mycolicibacterium clade and it is closely related to Mycolicibacterium chubuense. This is the first report of Mycobacteriosis of cultured koi carp.