Fish as bioindicators of mercury contamination in aquatic environments - an underestimated threat to consumer health

Fish are a recommended component of the diet, supplying complete proteins, vitamins, mineral salts, and omega-3 fatty acids. The presence of mercury in fish tissue, both freshwater and marine, is the effect of its accumulation in the aquatic environment and depends largely on the concentration of mercury in water as well as food. Most of mercury in fish tissues is present in the form of organic complexes, mainly methylmer - cury, which is much more toxic than metallic mercury. In organisms of predatory fish, such as shark, tuna, swordfish, or eel, mercury will be present in concentrations higher than in other species of fish. It is not just the result of their nutrition, but is also related to their age, mobility and habitat. In fish living near the bot - tom of a water body, the concentration of mercury will be much higher. It has to be noted that the ongoing climate change and increase in environmental contamination may significantly raise the bioavailability of mercury and its organic complexes in