The 12 Most Contaminated Fish to Avoid at the Grocery Store

Seafood is often celebrated as a healthy choice, rich in protein, omega-3 fatty acids, and essential nutrients. However, not all fish are created equal. Some species are prone to high levels of mercury, polychlorinated biphenyls (PCBs), and other environmental toxins, which can pose serious health risks—especially for pregnant women, young children, and frequent seafood consumers. Knowing which fish to avoid can help you make safer, smarter choices at the grocery store.

Here are the 12 most contaminated fish you should be cautious about:

1. Shark

Shark is a top predator, meaning it accumulates high levels of mercury over its long lifespan. Mercury exposure can affect the nervous system and is especially harmful to developing fetuses.

2. Swordfish

Swordfish is notorious for high mercury content. Regular consumption can lead to mercury poisoning symptoms such as memory issues, fatigue, and neurological problems.

3. King Mackerel

Unlike its milder cousin, the Atlantic mackerel, king mackerel is high in mercury. Health experts recommend avoiding it entirely, particularly for children and pregnant women.

4. Tilefish (Gulf of Mexico)

Tilefish from the Gulf of Mexico contain extremely high mercury levels, making them one of the most dangerous fish for frequent consumption.

5. Bigeye Tuna

Bigeye tuna, often used in sushi, is another large predator fish with significant mercury accumulation. Opt for smaller tuna varieties like skipjack to reduce risk.

6. Orange Roughy

Orange roughy is a deep-sea fish that lives for decades, absorbing toxins over time. Mercury levels can be alarmingly high in this species.

7. Chilean Sea Bass

Chilean sea bass is popular for its rich flavor, but it is high in mercury and often harvested unsustainably, making it a less healthy choice.

8. Marlin

Marlin is a large predatory fish with high mercury levels. Occasional consumption is acceptable for adults, but frequent intake should be avoided.

9. Bluefin Tuna

Bluefin tuna, prized for sushi and sashimi, contains significant mercury levels. Eating it sparingly is advisable, particularly for vulnerable populations.

10. Sablefish (Black Cod)

While flavorful, sablefish is known to accumulate higher levels of PCBs and mercury due to its long lifespan and fatty tissue content.

11. Imported Catfish

Imported catfish can carry contaminants from polluted waters. Choosing local, farm-raised, or certified organic catfish reduces exposure risks.

12. Atlantic Croaker

Atlantic croaker can contain both mercury and environmental toxins due to their habitat in polluted coastal areas. Limiting consumption is wise.

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Tips for Safer Seafood Consumption

• Choose smaller fish: Smaller fish typically contain less mercury than larger predatory species.

• Diversify your choices: Rotate fish types to minimize exposure to toxins.

• Look for certifications: Sustainable seafood certifications often indicate lower contamination levels.

• Mind the source: Wild-caught fish from cleaner waters are generally safer than some imported varieties.

Seafood can remain a healthy part of your diet if you make informed choices. By avoiding these 12 contaminated fish, you can enjoy the nutritional benefits of seafood without compromising your health.