5 Types of Fish You Should Limit Due to Higher Mercury Levels

Some fish may contain higher mercury levels—choose wisely for better health.

Fish is widely recognized as one of the healthiest sources of protein, providing high-quality nutrients and heart-friendly omega-3 fatty acids. However, not all fish are equally beneficial. Certain species are more likely to accumulate mercury, a toxic heavy metal that can pose health risks when consumed in large amounts over time.

Mercury occurs naturally in the environment but is also released through industrial activities, mining, and fossil fuel combustion. Once it enters rivers, lakes, and oceans, microorganisms convert it into methylmercury, a highly toxic form that accumulates in fish. Larger predatory fish tend to have the highest mercury concentrations because they consume many smaller fish throughout their lives.

Long-term exposure to excessive mercury may affect the brain, nervous system, kidneys, and cardiovascular system. Pregnant women, young children, and people who eat fish frequently are generally advised to be especially careful when choosing seafood.

1. Large Farmed Catfish

Some large farmed catfish may contain higher levels of contaminants depending on farming practices and environmental conditions. Experts recommend purchasing catfish from reputable suppliers that follow strict food safety standards and regulations.

2. Ocean Perch (Redfish)

Ocean perch is a long-lived species that may accumulate mercury over time. Because these fish often inhabit deeper waters and have longer lifespans, mercury concentrations can become higher than in many smaller fish.

3. Certain Types of Catfish

Not all catfish are the same. Mercury levels vary depending on species, habitat, and farming methods. Consumers should pay attention to food safety advisories and purchase seafood from trusted retailers.

4. King Mackerel

Although mackerel is an excellent source of omega-3 fatty acids, King Mackerel is known to contain significantly higher mercury levels than smaller species such as Atlantic or Atlantic chub mackerel. Health authorities often recommend limiting or avoiding King Mackerel, especially during pregnancy.

5. Eel

Eels can absorb pollutants from rivers, lakes, and coastal waters where they live. Depending on the environment, some eels may accumulate mercury and other contaminants. Choosing eel from reliable sources and consuming it in moderation is recommended.

Healthier Fish Choices

Fortunately, many fish remain excellent choices for a healthy diet while containing relatively low mercury levels. These include:

• Wild salmon
• Sardines
• Anchovies
• Trout
• Herring
• Pollock
• Tilapia (from reputable sources)

These species provide beneficial omega-3 fatty acids, protein, vitamin D, and essential minerals while generally containing much lower mercury concentrations than larger predatory fish.

Tips for Choosing Safer Seafood

To reduce mercury exposure while still enjoying the health benefits of fish:

• Choose smaller fish more often.
• Eat a variety of seafood instead of relying on one species.
• Buy fish from trusted suppliers with good quality control.
• Follow local seafood advisories if consuming wild-caught fish.
• Pregnant women and young children should follow national dietary guidelines regarding seafood consumption.

Fish remains an important part of a balanced diet. The key is selecting species that are lower in mercury while still providing valuable nutrients. By making informed choices, you can continue enjoying seafood while minimizing potential health risks.