Do catfish have more mercury than salmon?

December 11, 2025 •

2 min read

According to the U.S. Food and Drug Administration (FDA), both salmon and catfish are listed among the "best choices" for low-mercury fish, but the question remains: do catfish have more mercury than salmon? The answer lies in key factors like the type of fish and its sourcing, with the general consensus being that both are safe and low-mercury options for most consumers.

Quick Summary

Catfish and salmon are both low in mercury, with catfish often having even lower levels than farmed or wild salmon. Key factors like diet and sourcing (farmed vs. wild) impact mercury concentration. Both are considered safe, healthy choices for regular consumption according to FDA guidance.

Key Points

Mercury Levels: Both catfish and salmon are considered low-mercury fish by the FDA, with mercury levels well within safety guidelines for regular consumption.
Sourcing Matters: Farmed catfish and farmed salmon typically have lower mercury levels than their wild counterparts due to controlled diets and environments.
Omega-3 Content: Salmon is significantly higher in heart-healthy omega-3 fatty acids (EPA and DHA) compared to catfish, making it the better choice for boosting these nutrients.
Other Nutrients: Catfish offers a rich source of lean protein and Vitamin B12, while salmon provides a broader range of B vitamins and Vitamin D.
Consumption Guidelines: Both fish are recommended for regular consumption (2–3 servings per week) as part of a healthy diet, including for pregnant women and children.
Taste and Diet: The choice between catfish and salmon largely depends on taste preference and specific dietary needs, as both are excellent nutritional options.

Mercury Accumulation in Fish Explained

Mercury is a naturally occurring element that can build up in the aquatic food chain, primarily as methylmercury. The level of mercury in a fish is influenced by several factors, including its diet, size and age, habitat, and whether it is farmed or wild-caught. Fish higher on the food chain and older, larger fish tend to have higher mercury levels. Farmed fish often have lower mercury due to controlled diets and environments.

Catfish vs. Salmon: A Detailed Comparison

Catfish: Low Mercury and Nutrient-Dense

Catfish typically have low mercury levels because they are lower on the food chain. Farmed catfish, in particular, tend to have very low mercury concentrations due to controlled conditions. The FDA lists catfish as a low-mercury option suitable for pregnant women and children. Catfish also provides lean protein, B vitamins, and healthy fats.

Salmon: A Heart-Healthy Omega-3 Powerhouse

Salmon is renowned for its high omega-3 fatty acid content, beneficial for heart and brain health. Similar to catfish, salmon is considered a low-mercury fish. Studies suggest farmed salmon may even have lower mercury levels than wild salmon due to diet and faster growth. Both wild and farmed salmon mercury levels are generally within safety guidelines.

Comparison Table: Catfish vs. Salmon


Feature	Catfish (Farmed)	Salmon (Farmed)	Salmon (Wild)
Mercury Levels	Very Low (e.g., 0.024 ppm)	Low (e.g., 0.022 ppm)	Low (e.g., up to 3x higher than farmed)
Omega-3s	Good Source (Approx. 200 mg/3 oz)	Excellent Source (Approx. 1,800 mg/3 oz)	Excellent Source (High omega-3s)
Fat Content	Generally Leaner	High (Fatty Fish)	High (Fatty Fish)
Protein	High Lean Protein	High Lean Protein	High Lean Protein
FDA Ranking	Best Choice	Best Choice	Best Choice

Nutritional Differences and Overall Health Benefits

Beyond mercury, catfish and salmon offer different nutritional benefits. Salmon is significantly richer in omega-3 fatty acids EPA and DHA, vital for brain and heart health. Catfish excels in providing lean protein and Vitamin B12. Both contain selenium and are good sources of lean protein.

Consumption Guidelines and Smart Choices

Both catfish and salmon are excellent, low-mercury options. The choice often depends on desired nutritional intake. The FDA and EPA recommend 2–3 servings (8–12 ounces) of low-mercury fish per week for most adults. For high omega-3s, choose salmon. For a leaner option, catfish is suitable. Both are safe for pregnant women and children. Opting for farmed varieties can further minimize mercury concerns.

Conclusion: Both are Excellent, Low-Mercury Choices

Contrary to the question, both catfish and salmon are healthy, low-mercury fish options. The main distinction lies in their nutritional composition, with salmon providing more omega-3s and catfish offering more lean protein and Vitamin B12. Health authorities like the FDA recommend both as part of a balanced diet. The best choice for an individual depends on their dietary preferences and health goals. Refer to authoritative sources like the FDA for the latest advice on fish consumption.

Frequently Asked Questions

Yes, both catfish and salmon are on the FDA's list of 'best choices' for low-mercury fish and are safe for pregnant women, breastfeeding mothers, and young children to eat 2–3 times per week.

Salmon is a fattier fish and has a significantly higher concentration of omega-3 fatty acids (EPA and DHA) compared to the leaner catfish.

Farmed fish, including both catfish and salmon, generally have lower mercury levels than their wild-caught counterparts due to controlled feed and environment.

Mercury gets into fish through a process called bioaccumulation, where it moves up the food chain. Larger, predatory fish tend to have the highest levels.

Besides being low in mercury, catfish is an excellent source of lean protein, Vitamin B12, phosphorus, and selenium.

While both are healthy, salmon is superior for heart health due to its much higher content of EPA and DHA omega-3 fatty acids, which are known to reduce inflammation and support cardiovascular health.

While generally safe due to its low mercury content, it is recommended to vary your protein and fish sources to ensure a diverse intake of nutrients and minimize exposure to any single contaminant.