Which Fish Has the Least Mercury?

The Short Answer

The fish with the absolute lowest mercury levels are shellfish and small, short-lived fish.

Scallops (0.003 ppm), Shrimp (0.009 ppm), and Sardines (0.013 ppm) are the cleanest options you can buy. They are essentially mercury-free because they are at the bottom of the food chain and don't live long enough to bioaccumulate toxins.

For a main dinner fillet, Salmon is the clear winner. With an average of just 0.022 ppm mercury, you would need to eat roughly 50 pounds of salmon per week to reach the same mercury exposure as a single serving of swordfish.

Why This Matters

Mercury is a potent neurotoxin. It crosses the blood-brain barrier and the placenta, making it particularly dangerous for pregnant women and young children. High exposure is linked to developmental delays, cognitive deficits, and cardiovascular damage in adults.

The problem isn't the fish itself—it's biomagnification.

When small fish eat plankton containing trace mercury, it stays in their bodies. When a medium fish eats 10,000 small fish, it absorbs all their mercury. When a shark eats the medium fish, it inherits the toxic load of the entire chain. This is why size matters more than species: the larger and older the predator, the more toxic the meat.

The Data: Lowest to Highest

Here is the breakdown based on FDA monitoring data (averages in parts per million).

✅ The Cleanest (Eat Freely)

These species have negligible mercury levels (under 0.05 ppm).

⚠️ The Moderate (Eat Occasionally)

Safe for most adults once a week, but pregnant women should monitor intake.

🚫 The Toxic (Avoid)

These contain dangerous levels of mercury (near or above 1.0 ppm). Avoid these completely, especially if pregnant or feeding children.

The Tuna Trap: Light vs. White

Tuna is the most confusing category because "tuna" isn't one fish.

• Light Tuna (Skipjack) is a smaller fish. It averages 0.12 ppm mercury.
• White Tuna (Albacore) is a larger fish. It averages 0.35 ppm mercury.

Albacore has nearly 3x the mercury of Light tuna. If you eat tuna salad sandwiches, simply switching from "Solid White" to "Chunk Light" cuts your heavy metal intake by 65%.

Farmed vs. Wild Salmon

Unlike other nutrients where wild-caught often wins, mercury levels in salmon are low regardless of the source.

• Farmed Salmon: ~0.016 ppm
• Wild Salmon: ~0.022 ppm

Both are incredibly safe. While farmed salmon has other concerns (like PCB contamination or antibiotic use), mercury is not one of them. You can choose either option without worrying about heavy metal toxicity. Wild Vs Farmed Salmon

What to Look For

Green Flags:

• "Atlantic Mackerel" — This is the small, safe mackerel (0.05 ppm). Do not confuse it with King Mackerel.
• "Skipjack" — The specific species used in lower-mercury light tuna.
• MSC Certified — While this certifies sustainability, sustainable fisheries often target smaller, faster-reproducing fish which are naturally lower in mercury.

Red Flags:

• "King Mackerel" — The toxic cousin of the Atlantic Mackerel. Often just labeled "Mackerel" on menus in the South.
• "Ahi" or "Bigeye" — Common sushi tunas that are much higher in mercury than the stuff in cans.
• "Orange Roughy" — A deep-sea fish that can live to be 150 years old. It is a mercury sponge.

The Bottom Line

1. Prioritize the little guys. Sardines, anchovies, and shellfish (shrimp, scallops) are the safest seafood you can eat.

2. Make salmon a staple. It is the rare exception—a large-fillet fish that is consistently low in mercury and high in Omega-3s.

3. Swap your tuna. Trade Albacore (White) for Skipjack (Light) or, even better, swap it for canned sockeye salmon.

FAQ

Is cod high in mercury?

No. Cod is a lean white fish with low-to-moderate mercury levels (0.11 ppm). It is safe for most people to eat weekly, though it has about 5x more mercury than salmon.

Can I cook the mercury out of fish?

No. Mercury binds to the protein (muscle) of the fish. Unlike fat-soluble toxins like PCBs which can be reduced by trimming the skin and fat, mercury cannot be removed by cooking, cleaning, or freezing.

Is tilapia safe from mercury?

Yes. Tilapia is very low in mercury (0.013 ppm). However, it is also low in beneficial Omega-3s compared to salmon or sardines, making it a nutritionally "neutral" protein rather than a superfood. Is Tilapia Safe

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