The Common Fish With The Highest Consumable Mercury Levels

While fish is both a tasty and (usually) lean source of protein, it can also be a source of something much less desirable: Mercury. Mercury is a heavy metal that is also a neurotoxin to humans. This metal is found in trace amounts in various foods, but most people who are exposed to it through their food get that exposure from fish. 

Now, this does not mean that you should avoid fish altogether. Different varieties contain various levels of mercury. For instance, both sharks and tuna contain high amounts of the poisonous metal. However, there is one fish that stands far above the rest in terms of mercury content, and that is tilefish.

Tilefish is a type of fish commonly found on the waters off the east coast of the United States and in the Gulf of Mexico (via the National Oceanic and Atmospheric Administration). Large and containing white flesh, it has a taste similar to shellfish such as lobster. However, FDA data show that it can contain levels of mercury that far exceed even famously mercury-high fish such as tuna, with some tilefish clocking in at 1.123 parts per million (ppm) of mercury, which is above the agency's limit of 1 ppm of mercury in fish and more than 10 times that of lobster (via FDA).

When it comes to mercury content, not all tilefish is created (or caught) equally. The ones caught in the Gulf of Mexico have much higher levels (1.123 ppm) than those caught in the Atlantic, which only have a mean mercury ppm of 0.144, around the same as skipjack tuna. These results seem to extend beyond just tilefish, however. Studies — including one from Environmental Research – have shown that many fish caught in the Gulf of Mexico contain higher levels of mercury than fish caught in other bodies of water. 

Consuming large amounts of mercury can be hazardous to your health, particularly for those who are pregnant, as exposure can cause numerous birth defects. This might make some people wonder whether it's safe to eat tilefish and other high-mercury fish like swordfish (which falls just below tilefish in the FDA's ranking). Generally, for healthy people, it's okay to eat swordfish and tilefish occasionally. Fish with lower levels of mercury, like shrimp or haddock, are safe to eat about twice a week, according to Healthline. However, the FDA says that children and those who are pregnant (or may become pregnant) should avoid tilefish (as well as swordfish, shark, and king mackerel) so, you may want to take that into account when deciding what's for dinner.