Mycobacterium marinum is the most important fish tuberculosis agent. Turkey is an important Mediterrenean country in terms of sea bass, sea bream and trout production. In this work, a total of 1050 fish samples (300 sea bass, 300 sea bream, 450 trout, respectively) taken randomly from 20 sea bass and sea bream (No:1-20), and 15 trout (No: 21-35) farms, were analysed using a combination of culture-based and molecular (Reverse Hybridisation) methods for Mycobacterium spp. The majority of samples were negative for mycobacteriosis. However, isolates that were positive by Reverse Hybridisation for M. marinum were isolated and identified from 60 fish (30 sea bass and 30 sea bream samples) from two cages of one farm in the Milas/Mugla province (Southeastern part of the Aegean Sea). This is the first M. marinum isolation from cultured sea bass and sea bream in Turkey.