13 Fish You Shouldn't Eat Due to High Mercury and Contamination

In the realm of nutrition, fish is often heralded as a superfood, rich in omega-3 fatty acids, high-quality protein, and essential nutrients. However, not all fish are created equal. Some types of fish, due to various environmental, biological, and chemical factors, pose significant health risks. From mercury contamination to overfishing, there are several reasons why certain fish should be avoided or consumed sparingly. This comprehensive guide will delve into 13 types of fish you might want to reconsider before placing them on your dinner plate.

1. Shark

Sharks, often revered as apex predators, accumulate high levels of mercury in their tissues due to their position at the top of the food chain. Mercury is a potent neurotoxin that can cause serious health problems, particularly in pregnant women and young children. Chronic exposure to mercury can lead to cognitive impairments, cardiovascular issues, and immune system dysfunction. Given the high mercury content in sharks, it's advisable to avoid consuming shark meat altogether.

2. Swordfish

Similar to sharks, swordfish are large predatory fish that accumulate significant amounts of mercury over time. The FDA and EPA both advise that pregnant women, nursing mothers, and young children avoid swordfish due to the risks associated with mercury exposure. Even for the general population, swordfish should only be consumed sparingly. Mercury toxicity can lead to a range of neurological and developmental problems, making it crucial to limit exposure.

3. King Mackerel

King mackerel is another fish that is high in mercury. While mackerel is generally considered a healthy choice, king mackerel, in particular, should be avoided. The high mercury levels in king mackerel can affect brain function, particularly in fetuses and young children, leading to developmental delays and cognitive impairments. Opt for safer alternatives like Atlantic mackerel, which is lower in mercury and provides similar health benefits.

4. Tilefish

Tilefish, especially those from the Gulf of Mexico, are known for their exceptionally high mercury levels. In fact, the FDA ranks tilefish as one of the fish with the highest mercury content. Regular consumption of tilefish can significantly increase mercury levels in the body, posing severe health risks. Due to these concerns, tilefish should be avoided, especially by vulnerable populations such as pregnant women and children.

5. Bigeye Tuna

Tuna is one of the most popular fish consumed worldwide, but not all types of tuna are safe to eat frequently. Bigeye tuna, often used in sushi, is particularly high in mercury. While it is a rich source of omega-3 fatty acids, the risks associated with mercury exposure outweigh the benefits. Canned light tuna is a safer alternative, as it contains lower levels of mercury compared to bigeye and other large tuna species like bluefin.

6. Orange Roughy

Orange roughy, also known as slimehead, is a deep-sea fish that can live for over 100 years. Because of their long lifespan, they accumulate high levels of mercury over time. Additionally, orange roughy is often overfished, leading to concerns about sustainability. The combination of high mercury content and environmental concerns makes orange roughy a fish to avoid.

7. Chilean Sea Bass

Chilean sea bass, also known as Patagonian toothfish, is another long-lived species that accumulates mercury. While it is a popular choice in fine dining, the health risks associated with its consumption are significant. Moreover, Chilean sea bass is often caught using methods that contribute to environmental degradation, including the destruction of sea floors and bycatch of endangered species. Due to these factors, it’s advisable to choose other fish that are lower in mercury and more sustainably sourced.

8. Grouper

Grouper is a large predatory fish that is prone to high mercury accumulation. This popular fish, often served in restaurants, can pose serious health risks if consumed frequently. Grouper is also subject to overfishing, which raises sustainability concerns. For those who enjoy the taste of grouper, it’s wise to limit consumption and seek out sustainably sourced alternatives with lower mercury levels.

9. Marlin

Marlin, a prized game fish, is not only high in mercury but also at risk due to overfishing. The high levels of mercury in marlin make it unsafe for regular consumption, particularly for pregnant women and children. Additionally, the decline in marlin populations due to overfishing has led to concerns about the long-term sustainability of this species. Avoiding marlin helps protect your health and contributes to the conservation of marine ecosystems.

10. Atlantic Bluefin Tuna

Atlantic bluefin tuna is one of the most sought-after fish in the world, especially in sushi. However, it is also one of the most endangered species due to overfishing. Bluefin tuna is high in mercury, making it unsafe for frequent consumption. The combination of high mercury levels and the species' endangered status makes Atlantic bluefin tuna a fish to avoid altogether.

11. Escolar

Escolar, sometimes marketed as “white tuna,” is a fish that can cause digestive issues due to its high oil content. This fish contains a waxy ester called gempylotoxin, which is indigestible by humans and can lead to severe gastrointestinal distress, including diarrhea. Despite being marketed as a delicacy, the potential for adverse digestive effects makes escolar a fish to steer clear of.

12. Pangasius (Swai/Basa)

Pangasius, often sold as swai or basa, is a freshwater fish commonly farmed in Southeast Asia. While it is an affordable option, there are concerns about the farming practices used, which often involve the use of antibiotics and other chemicals. Moreover, pangasius is frequently exposed to contaminated water, leading to potential health risks. The combination of questionable farming practices and potential contamination makes pangasius a fish best avoided.

13. Farmed Salmon

Salmon is often considered a healthy choice, but farmed salmon poses several concerns. Farmed salmon are typically raised in crowded pens, leading to higher levels of contaminants like polychlorinated biphenyls (PCBs) and dioxins. Additionally, farmed salmon are often treated with antibiotics and fed an unnatural diet, which can affect the nutritional quality of the fish. Opting for wild-caught salmon is a safer and healthier alternative.

Conclusion

While fish is an important part of a healthy diet, being selective about the types of fish you consume is crucial for your health and the environment. High levels of mercury, unsustainable fishing practices, and contamination are significant concerns that should guide your choices. By avoiding the fish listed above and opting for safer, sustainably sourced alternatives, you can enjoy the benefits of seafood without compromising your well-being.