The objective of the present study was to determine the activities of antioxidant enzymes and malondialdehyde levels in various species of bony fishes, cartilaginous fishes and mollusks living at different depths in coastal habitats in the Mediterranean Sea off the coast of Benghazi. Sixteen marine organisms were collected, and the analyses were performed on the muscles and liver. Some species under study are significant for human health and nutrition in addition to their economic importance. The antioxidant enzymes, such as superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx) and terminal markers of lipid peroxidation, thiobarbituric acid reactive substances, expressed as malondialdehyde (MDA) were investigated. The results revealed a link between dietary abundance, trophic behavior, feeding habit and oxidative stress, but the antioxidant response varies depending on the organism.