King mackerel's mercury levels

As a rule both salmon and mackerel contain negligible levels of heavy metal pollutants such as mercury compared to other species of fish. That said, one species of mackerel known as the king mackerel contains a good deal of mercury and needs to be avoided, according to the American Heart Association. King mackerel is a large predatory fish indigenous to the Gulf of Mexico and the South Atlantic. A reading of around 1 part per million of mercury in any species of fish is considered high, and king mackerel contains a 0.73 mean mercury level per parts per million. Stick to smaller species of mackerel to keep mercury intake within a safe range.