Trace elements were analyzed in fish of commercial interest to determine their importance in marine systems of the Western Indian Ocean and their bioaccumulation patterns. The results are equivalent or lower than levels reported in ichthyofauna worldwide. Certain values of muscular Cd, Hg, Pb and Zn were however above thresholds for human consumption. Levels varied among tissues, species and with fish length, but were seldom influenced by the nutritional condition of the fish, its gender and its reproductive status. Correlations between hepatic Hg and Se levels in Swordfish (r2 = 0.747) and Yellowfin Tunas (r2 = 0.226), and among metallothionein linking metals imply the existence of detoxification processes in these species. Differences in levels between fish from the Mozambique Channel and Reunion Island probably reflect differences of diets rather than differences of elemental availability in both environments.