Mycobacterium infections Aetiological agent/s Infections induced by a group of species belonging to the genus Mycobacterium including Mycobacterium marinum, Mycobacterium chelonae, Mycobacterium fortuitum. Epidemiology Host/s (species; age): Seabass (Dicentrarchux labrax), meagre (Argyrosomus regius), seabream (Sparus aurata). Chronic disease occurring on large size fish. Morbidity and mortality rates: chronic mortality usually lower than 5-10%. Transmission: horizontal transmission from fish to fish through skin injuries and digestive track or from the environment, water and related biofilm being the natural reservoir of the pathogen. Vertical transmission is reported in some species but not documented in aquaculture fish. Factors (environmental, others) for disease outbreak: Temperature dependent above 16°C Factors influencing the occurrence of skin or intestinal micro lesions. Zoonotic disease