Which fish has the least mercury? A guide to safe seafood choices

According to the FDA, certain small species of fish contain significantly lower levels of mercury than their larger counterparts. This makes understanding which fish has the least mercury crucial for informed and healthy dietary choices, especially for vulnerable populations like pregnant women and young children.

Quick Summary

This guide provides a comprehensive breakdown of fish mercury levels, identifying species that are the safest for regular consumption. Learn about the factors influencing mercury content, how to read advisory lists, and make the most nutritious and safe seafood choices for your diet.

Key Points

• Small, Short-Lived Fish are Safest: Smaller fish like sardines, anchovies, and Atlantic mackerel accumulate the least amount of mercury due to their position lower on the food chain and shorter lifespan.

• Apex Predators Have Highest Mercury: Large, long-lived predators such as shark, swordfish, and king mackerel contain the highest mercury levels through the process of bioaccumulation.

• Canned Light Tuna is Safer: When it comes to tuna, canned light tuna (made from skipjack) has significantly lower mercury than canned albacore or fresh tuna steaks.

• Check FDA and EPA Guidelines: The U.S. Food and Drug Administration and Environmental Protection Agency provide comprehensive, regularly updated advice on safe fish consumption, especially for sensitive populations.

• Consult Local Advisories for Wild-Caught Fish: If eating wild-caught fish, especially from local waterways, check for specific regional advisories that account for local contamination.

• Benefits of Fish Still Outweigh Risks: For most people, the health benefits of eating fish, rich in omega-3s, outweigh the mercury risk as long as they choose low-mercury options and eat a varied diet.

Understanding Mercury in Fish: Why it Matters

Mercury is a naturally occurring element that, when released into the environment, is converted by bacteria into a more harmful organic form called methylmercury. This methylmercury bioaccumulates, meaning its concentration increases as it moves up the food chain. Larger, predatory fish that live longer tend to have the highest levels because they consume many smaller fish that have already absorbed mercury.

The health risks associated with high mercury intake are most significant for developing fetuses, young children, and individuals with a high consumption of contaminated seafood. High exposure can affect the nervous system and brain development. Therefore, choosing lower-mercury fish is a key strategy for mitigating this risk while still enjoying the nutritional benefits of seafood, such as essential omega-3 fatty acids.

The Top Low-Mercury Fish and Shellfish

Fortunately, many delicious and nutritious fish and shellfish options are low in mercury. The Food and Drug Administration (FDA) provides extensive guidance on these choices, categorizing them to help consumers make informed decisions. Here are some of the best choices for minimal mercury exposure:

• Anchovies: Tiny, but mighty in flavor and nutrients, with some of the lowest mercury levels.
• Atlantic Mackerel: Not to be confused with larger king mackerel, this smaller variety is a safe and healthy choice.
• Catfish (farmed): Farmed catfish typically has very low mercury levels.
• Cod: A mild-flavored white fish that is a 'Best Choice' according to the FDA.
• Herring: An oily fish rich in omega-3s with a very low mercury content.
• Oysters: These mollusks are not only delicious but also very low in mercury.
• Pollock: Often used in fish sticks and fast-food fish sandwiches, pollock is a consistently low-mercury option.
• Salmon: Wild or farmed, salmon is a great source of omega-3s and is low in mercury.
• Sardines: A fantastic, nutrient-dense choice with extremely low mercury concentrations.
• Scallops: Similar to other shellfish, scallops contain very little mercury.
• Shrimp: One of the lowest-mercury seafood options available.
• Tilapia: This mild white fish is a popular low-mercury option.
• Trout (freshwater): Another healthy, low-mercury fish, particularly when farm-raised.
• Tuna (Canned Light): Canned light tuna (typically skipjack) is a better choice than canned albacore or fresh tuna, which have higher mercury content.

Comparing Mercury Levels in Common Fish

This table illustrates the stark difference in mercury levels between low- and high-risk species, based on average concentrations (parts per million or ppm) reported in various studies and advisory lists.

Fish Species	Mercury Level (ppm)	Consumption Guideline	Reason for Level
Shrimp	0.001	Best Choice	Lowest on the food chain, short-lived
Salmon	0.022	Best Choice	Lower on the food chain, short lifespan
Sardines	0.013	Best Choice	Tiny size, lowest on the food chain
Canned Light Tuna	0.128	Best Choice	Smaller, younger tuna species used for canning
Albacore Tuna	0.35	Good Choice (Limit)	Larger species than skipjack tuna
Swordfish	0.995	Choice to Avoid	Large, long-lived predator at top of the food chain
King Mackerel	0.730	Choice to Avoid	Large, long-lived predator
Shark	0.979	Choice to Avoid	Apex predator, bioaccumulation

How to Choose the Safest Seafood

When navigating the seafood aisle or ordering at a restaurant, a few simple rules can help minimize your mercury exposure. The general principle is to choose smaller, shorter-lived species over larger, longer-lived predators. This is because the process of bioaccumulation disproportionately affects fish higher up the food chain.

Another consideration is the sourcing. Some research suggests that farmed fish can sometimes have lower mercury levels than their wild-caught counterparts, although this varies depending on the specific species and farming practices. The type of tuna also matters significantly; canned light tuna is a much safer bet than fresh bigeye or albacore tuna.

For those who fish recreationally, it is important to be aware of local fish advisories, as mercury levels in freshwater fish can vary greatly by location. These advisories provide specific guidance based on local contamination. By being mindful of these factors, you can enjoy seafood with confidence, knowing you are making the healthiest possible choice for you and your family.

Conclusion: Prioritizing Health While Enjoying Seafood

Choosing fish with the least mercury is a proactive health decision that allows you to reap the numerous benefits of seafood, such as protein and omega-3s, while minimizing risk. By favoring smaller, low-mercury species like salmon, sardines, and shrimp, you can maintain a balanced and healthy diet. Always consult reliable sources like the FDA for the latest consumption advice, particularly if you are pregnant, nursing, or feeding young children. A mindful approach to selecting seafood is the best way to enjoy its flavor and nutritional value safely. For more detailed and current information, refer to the official FDA guidelines.

Frequently Asked Questions

Which specific fish species are the lowest in mercury?

The fish species lowest in mercury include salmon, sardines, anchovies, herring, shrimp, scallops, and tilapia.

Are all types of tuna high in mercury?

No, not all tuna is high in mercury. Canned light tuna (skipjack) is low in mercury and considered a 'Best Choice,' while fresh or canned albacore tuna and bigeye tuna are higher in mercury.

Why do larger fish have more mercury?

Larger, predatory fish like shark and swordfish have higher mercury levels because they eat many smaller fish, and mercury accumulates in their systems over their longer lifespans. This process is known as bioaccumulation.

Is farm-raised or wild-caught fish lower in mercury?

Research suggests that farmed fish may sometimes contain less mercury than wild-caught fish, but this can vary. Ultimately, the best way to minimize exposure is to choose smaller species, regardless of whether they are farmed or wild.

How often can I safely eat fish?

For most adults, health organizations recommend eating two to three servings of a variety of low-mercury fish per week. For higher-mercury options, limit consumption.

What are the risks of consuming too much mercury?

Excessive mercury consumption, especially methylmercury found in fish, is a neurotoxin that can cause damage to the nervous system. The risks are highest for pregnant women, nursing mothers, and young children.

Do shellfish contain mercury?

Most shellfish, including shrimp, scallops, clams, and oysters, contain very low levels of mercury and are generally considered safe choices for regular consumption.