Do Catfish Contain a Lot of Mercury? An In-Depth Look

December 24, 2025 •

4 min read

According to the U.S. Food and Drug Administration (FDA), catfish are on the list of "Best Choices" for fish with the lowest mercury levels. This may surprise many who assume all large fish carry a high mercury risk, but the truth is that catfish are a safe and healthy seafood choice for most people, including pregnant women and children.

Quick Summary

Catfish, especially farm-raised varieties, are considered a low-mercury fish and a safe option for regular consumption. Factors like farming practices and the fish's diet influence mercury content. It is important to distinguish between catfish and other high-mercury species to make informed dietary decisions.

Key Points

Low Mercury Content: The U.S. FDA lists catfish as a "Best Choice" due to their very low levels of mercury, making them a safe option for consumption.
Farm-Raised Advantage: U.S. farm-raised catfish are particularly low in mercury because they are raised in controlled environments and fed monitored diets.
Wild-Caught Variance: Wild-caught catfish can have varying mercury levels depending on the water source, but still remain lower than predatory fish.
Nutritional Value: Catfish is an excellent source of lean protein, B vitamins, and healthy omega fatty acids.
Safe for All: Because of their low mercury concentration, catfish are recommended for all populations, including pregnant women, nursing mothers, and children.
Check Local Advisories: For wild-caught catfish, it is wise to consult local fish advisories to ensure the specific water body isn't contaminated.

Understanding Mercury in Seafood

Mercury is a naturally occurring element that enters the aquatic ecosystem through both natural and human activities, such as industrial emissions. In water, bacteria convert it into a highly toxic form called methylmercury, which is then absorbed by small organisms. This methylmercury moves up the food chain, a process known as biomagnification. As a result, larger, older, and more predatory fish tend to accumulate significantly higher concentrations of mercury in their tissue. For this reason, regulatory bodies like the FDA and EPA advise consumers to limit their intake of certain high-mercury fish.

Why Are Catfish Considered Low-Mercury?

Catfish are notably lower in mercury compared to many other popular fish species. Their place in the food chain is a key factor. Catfish are generally bottom-feeders or omnivores, consuming a diet of smaller aquatic organisms, plants, and insects rather than large fish. This positioning at a lower trophic level means they have far less exposure to the biomagnification process that drives up mercury levels in bigger predators like shark or swordfish.

Additionally, the rise of modern aquaculture has made farm-raised catfish a particularly low-mercury option. U.S. Farm-Raised Catfish are raised in controlled environments and fed a scientifically formulated, high-protein diet. This eliminates the risk of mercury absorption from polluted waterways, which can affect wild-caught fish, especially larger, older specimens from contaminated lakes or rivers.

Farm-Raised vs. Wild-Caught Catfish

It is essential to understand the distinction between farm-raised and wild-caught catfish, as it can impact their nutritional profile and contaminant levels. While both are generally low in mercury, farm-raised varieties offer a more predictable and often lower mercury content due to their controlled environment.

Benefits of Farm-Raised Catfish

Controlled Environment: Raised in contained, freshwater ponds, minimizing exposure to environmental pollutants and toxins.
Consistent Diet: Fed a monitored diet, which ensures a more reliable and lower mercury concentration.
Stringent Regulation: U.S. farm-raised catfish are subject to strict food safety regulations and inspections by government bodies like the USDA.

Considerations for Wild-Caught Catfish

Source Matters: The mercury content of wild-caught catfish can vary depending on the specific waterway. Larger, older fish caught in polluted areas may have higher mercury levels.
Local Advisories: Always check local fish and shellfish advisories from environmental agencies, especially when catching your own fish from local lakes or rivers.

Comparison Table: Catfish vs. High-Mercury Fish


Feature	Catfish	High-Mercury Fish (e.g., Swordfish, Shark)
Mercury Content	Very low to low, especially when farm-raised	Very high due to biomagnification
Trophic Level	Lower on the food chain, omnivorous	Top-tier predators, consuming smaller fish
Typical Size	Smaller and younger than top predators	Larger, longer-lived fish
Regulatory Advice	"Best Choice" for all populations, including pregnant women and children	"Choices to Avoid" or limited consumption advised for all, especially at-risk groups
Source	Commonly farm-raised under controlled conditions	Wild-caught, often in open ocean environments

Catfish and Healthy Eating

Beyond its low mercury content, catfish is a nutritional powerhouse that provides several health benefits. A single serving is an excellent source of high-quality, lean protein, which is essential for muscle growth and repair. It also contains moderate levels of heart-healthy omega-3 and omega-6 fatty acids. These fatty acids are crucial for cognitive function and reducing inflammation. Catfish also provides a boost of vital nutrients like vitamin B12, selenium, and phosphorus.

For those seeking a safe and nutritious seafood option, the low mercury levels in catfish make it a superior choice, especially when sourced responsibly. Information about responsible fishing and aquaculture practices can be found at reputable sources like the Monterey Bay Aquarium Seafood Watch.

Guidelines for Safe Consumption

For most people, the nutritional benefits of eating catfish far outweigh any potential risks from mercury. Regulatory bodies provide clear recommendations to help consumers make smart choices. The FDA advises pregnant women, breastfeeding women, and young children to eat 2 to 3 servings per week from the "Best Choices" list, which includes catfish. For the general population, eating a variety of seafood, with a focus on low-mercury options, is the best strategy for reaping health benefits while minimizing risk.

Conclusion: Catfish is a Smart and Safe Seafood Choice

To answer the question, "Do catfish contain a lot of mercury?" the resounding answer is no. Catfish rank among the safest seafood options in terms of mercury content, largely due to their lower position in the food chain and the prevalence of well-regulated, farm-raised production. By choosing catfish, particularly U.S. farm-raised varieties, consumers can enjoy a nutritious, low-mercury protein source. This makes it an excellent choice for individuals, families, and those with increased sensitivity, ensuring that you can enjoy the benefits of seafood without excessive worry about heavy metals.

Frequently Asked Questions

From a mercury perspective, U.S. farm-raised catfish often has more consistent and lower levels because it's raised in controlled freshwater ponds with a regulated diet. Wild-caught levels can vary more based on the fish's age and local water conditions.

Large, predatory fish that are high on the food chain and live longer tend to have the highest mercury levels. Examples include shark, swordfish, king mackerel, and tilefish from the Gulf of Mexico.

Yes, catfish is considered a very safe option for pregnant women due to its low mercury content. The FDA includes it on the "Best Choices" list, recommending 2–3 servings per week for expectant mothers.

Mercury from industrial and natural sources enters waterways, where it is converted into methylmercury. This compound is then absorbed by algae and builds up in fish as it moves up the food chain through consumption.

For most adults, eating two or more servings of low-mercury fish like catfish per week is considered safe and beneficial. Pregnant and breastfeeding women are advised to follow the 2–3 servings per week recommendation from the FDA.

Generally, yes, though mercury content can be slightly higher in older, larger wild-caught catfish. However, even these levels are significantly lower than those found in larger predatory species.

Catfish contains substantially less mercury than most tuna varieties. While canned light tuna is on the low-mercury list, albacore and bigeye tuna have higher levels. Catfish is a consistently lower mercury option across the board.