A well known characteristic of the oxidative metabolism of Antarctic fishes is their preferential utilization of the lipid metabolic pathway. Since oxidative metabolism may lead to a significant production of oxygen‐derived free radicals, which may have several harmful effects on biological structures, it seemed worthwhile to investigate the presence, in various tissues from different Antarctic fishes, of those ions and molecules which are known to be at the basis of the antioxidant defense mechanisms. Hence, the Coenzyme Q and trace elements (selenium, copper, and zinc) content of tissues from several Antarctic fishes was determined and compared with that of non‐Antarctic species. Unlike temperate fishes, in which the Coenzyme Q is Q10, all the Antarctic species examined displayed the homolog Q9form. This particular finding was related to the difference in the crystallisation temperature existing between Coenzyme Q10and Coenzyme Q9. Taken together, the results indicate a higher level of antioxidant defenses for Antarctic species, with respect to temperate fishes. This may be considered a stimulating basis for further studies on the adaptation mechanisms centered on the oxidative metabolism of organisms living in extreme environments.