33Mycobacterium marinum is the causative agent for the tuberculosis-like disease 34 mycobacteriosis in fish and skin lesions in humans. Ubiquitous in its geographical 35 distribution, M. marinum is known to occupy diverse fish as hosts. However, information 36 about its genomic diversity is limited. Here, we provide the genome sequences for 15 M. 37 marinum strains isolated from infected humans and fish. Comparative genomic analysis of 38 these and four available genomes of the M. marinum strains M, E11, MB2 and Europe 39 reveal high genomic diversity among the strains, leading to the conclusion that M. 40 marinum should be divided into two different clusters, the "M"-and the "Aronson"-type. 41We suggest that these two clusters should be considered, if not two separate species, at 42 least two M. marinum subspecies. Our data also show that the M. marinum pan-genome for