The fish itself is not dangerous, dangerous mercury that it contains because of the increase of industrial water pollution. Mercury is very toxic and dangerous for the fetus and to breast-fed infant. Such exotic for us long-lived and large fish like shark, sword-fish, king mackerel, contain high concentrations of mercury and are not recommended for human consumption. The safest for the content of mercury is sea products like shrimp, tuna and salmon, pollock, catfish, they are not recommended to use more often than once a week.
