What Fish Has Mercury in Them? | Safer Choices Explained

Many people hear about mercury in seafood and quietly wonder what fish have mercury in them, which ones are fine every week, and which ones should stay on the rare list. You do not need to give up fish to stay safe, but you do need a clear map of higher and lower mercury choices.

This guide brings together government and health agency advice so you can see which fish carry the most mercury, how much is safe for different ages, and simple swaps that keep the benefits of seafood while trimming down the risk.

Why Mercury Builds Up In Fish

Mercury is a metal that reaches oceans and lakes from natural sources and from human activity. In water, certain microbes turn it into methylmercury, a form that passes easily into living tissue and then from smaller creatures up through the food chain. Larger, older fish have had more time to eat smaller ones, so their bodies hold more mercury.

The World Health Organization notes that people are mainly exposed to methylmercury when they eat fish and shellfish, and that high exposure can harm the nervous system, especially for unborn babies and young children. WHO mercury and health facts describe these risks in more detail.

Mercury binds tightly to fish muscle, not just the skin, so trimming fat or removing the skin does not lower levels by much. Cooking methods do not remove methylmercury either. The most effective step is choosing species that sit lower on the mercury scale and eating higher mercury fish less often.

What Fish Has Mercury in Them? Risk Levels At A Glance

Every fish contains at least a trace of mercury, yet the amount varies a lot. Health agencies group fish into broad bands: high mercury, medium mercury, and low mercury. The U.S. Food and Drug Administration (FDA) and U.S. Environmental Protection Agency (EPA) publish a joint chart that places dozens of fish into these lists and ties them to suggested weekly servings for adults, pregnant people, and children. FDA advice about eating fish shows this chart in full.

Below is a summary view so you can see where common choices land. Exact values differ a bit between studies, yet the same names show up on the high list again and again.

High-Mercury Fish To Limit

High-mercury fish are mostly large hunters that live long lives. Many national guidelines recommend avoiding these if you are pregnant, might become pregnant, or if you are serving young children, and keeping them to rare treats for everyone else.

• Shark
• Swordfish
• King mackerel
• Tilefish from the Gulf of Mexico
• Bigeye tuna (often used in some sushi and sashimi)
• Marlin
• Orange roughy

In the UK, for instance, national health advice asks pregnant people and children to avoid shark, swordfish and marlin completely, and tells other adults to keep them to no more than one portion per week. NHS fish and shellfish guidance gives detailed examples.

Medium-Mercury Fish: Safe In Small Amounts

Medium-mercury fish usually sit in the middle of the food chain. They bring valuable nutrients but should not fill every seafood serving, especially for those who are pregnant or feeding young children. Examples often listed in the middle band include:

• Albacore (white) tuna, fresh or canned
• Some types of grouper
• Chilean sea bass (Patagonian toothfish)
• Some types of snapper

Joint guidance from the FDA and EPA suggests that people who are pregnant or breastfeeding keep albacore tuna to one serving per week and choose lower mercury fish for the remaining seafood meals. EPA–FDA advice about eating fish and shellfish explains these limits.

Low-Mercury Fish You Can Eat Often

Low-mercury fish are usually smaller or shorter lived. Public health agencies place many of these species in a “best choices” group that can appear on the table two or three times per week for most people.

• Salmon
• Sardines
• Anchovies
• Herring
• Atlantic mackerel (not king mackerel)
• Cod, pollock, haddock
• Tilapia, catfish, trout
• Shrimp and most other common shellfish

These fish bring protein and omega-3 fats with far lower mercury exposure than big predatory species. For most families, building a rotation from this group is the simplest way to enjoy seafood while staying under methylmercury intake limits recommended by expert panels in Europe and North America. EFSA opinion on mercury and methylmercury in food shaped many of these thresholds.

Summary Table Of Common Fish And Mercury Level

The table below groups well-known fish by typical mercury category. Local advisories may differ, so always check regional guidance when you often eat fish from one area.

Fish	Typical Mercury Category	Practical Note
Shark	High	Avoid during pregnancy and childhood; rare choice for others.
Swordfish	High	Treat as an occasional meal; often listed on “do not eat” lists for pregnant people.
King Mackerel	High	Different from Atlantic mackerel; keep off the weekly menu.
Bigeye Tuna	High	Common in some sushi; choose other tuna types for frequent meals.
Albacore (White) Tuna	Medium	Limit to one serving per week for pregnant people and for children.
Salmon	Low	Fits well into a two-to-three-serving weekly pattern for most adults.
Sardines	Low	Small oily fish with very low mercury and plenty of omega-3 fats.
Cod	Low	Lean white fish; works for family dinners and fish pies.
Shrimp	Low	Easy option when you want seafood with minimal mercury.
Tilapia	Low	Mild taste that suits children and those new to fish.

What Fish Have Mercury In Them And Safer Seafood Picks

Knowing that large predatory fish carry more mercury is helpful, yet most people shop by name, not by food chain position. This section lines up common choices with gentler swaps so you still enjoy the meals you like.

Tuna Choices: Light Vs White

Canned tuna is a regular lunch staple in many homes. The label gives a big clue about mercury level. Canned light tuna (usually skipjack) tends to sit in the low group. Canned white or albacore tuna usually lands in the medium group and carries more methylmercury per serving.

For adults who are not pregnant, a mix of canned light tuna and other low-mercury fish keeps intake in a safe range. For pregnant people, breastfeeding people, and children, many health agencies suggest using canned light tuna more often and keeping albacore to one small serving per week at most.

Swaps For High-Mercury Steaks

Grilled swordfish or shark steaks may sit on restaurant menus, yet you can order something similar with far less mercury. If you like firm, meaty fish, try:

• Grilled salmon or trout fillets in place of swordfish.
• Mahi-mahi or cod loins instead of marlin or shark.
• Thick tuna steaks from lower mercury species when available, eaten in rotation with other fish.

These alternatives still hold together on the grill or in a pan but bring far lower mercury exposure over the year.

Shellfish And Mercury

Most shellfish sit low on the mercury scale because they are short lived and eat low on the food chain. Shrimp, mussels, clams, scallops and oysters usually appear in the “best choices” column of the FDA chart. Crab can vary: white crab meat sits low, while brown meat is sometimes restricted in national guidance due to higher levels of certain contaminants.

Shellfish still need proper storage and cooking to avoid foodborne illness, yet from a mercury point of view they tend to be among the gentler options for adults and older children.

How Much Fish Is Safe Per Week?

Health agencies try to balance the nutrient benefits of fish with limits on mercury intake across a whole week. Numbers differ slightly by country, yet the patterns stay close: more servings of low-mercury fish, tight limits on high-mercury fish, and a cap on medium-mercury choices.

Adults Who Are Not Pregnant

For most adults who are not pregnant, many national guidelines encourage two to three servings of fish per week, mainly from low-mercury species such as salmon, sardines, cod, pollock, haddock, trout and shellfish. Within that pattern, an occasional serving of a medium-mercury fish like albacore tuna is usually within advisory limits.

Large high-mercury fish like shark, swordfish, king mackerel and bigeye tuna sit in the “rare treat” zone. Enjoying them once in a while is one thing; eating them every week raises methylmercury intake and can push average exposure above safety thresholds set by agencies such as EFSA and WHO.

Pregnant Or Breastfeeding People

During pregnancy and breastfeeding, the brain of the baby is still developing and is more sensitive to methylmercury. The FDA and EPA advise two to three servings per week of fish from a list of lower-mercury choices, such as salmon, sardines, trout, pollock, shrimp and anchovies, and they give a serving size of about 4 ounces (roughly 113 grams) of cooked fish for adults in this group. EPA guidelines for eating fish that contain mercury give more detail.

High-mercury fish such as shark, swordfish, king mackerel, tilefish from the Gulf of Mexico, marlin, orange roughy and bigeye tuna sit on the “do not eat” list during pregnancy in many countries. Albacore tuna is usually limited to one serving per week in this stage of life.

Children And Teens

Children can benefit from nutrients in fish for growth and brain development, but their smaller body size means the same portion brings a higher dose of mercury. Many national charts give smaller serving sizes by age, starting at around 28 grams for toddlers and rising to 113 grams for older teens.

In general, children can have two servings per week from low-mercury fish, while very high-mercury species like shark, swordfish and marlin should be avoided completely. Medium-mercury fish are best kept as an occasional choice, not a weekly habit. For children who eat a lot of canned tuna, shifting toward canned light tuna and rotating with salmon, sardines or trout can lower overall exposure.

Weekly Fish Servings Guide

The guide below gives a simple snapshot of how many weekly servings often appear in public health advice. Local rules vary, so use this as a starting point and cross-check against the chart in your country.

Group	Low-Mercury Fish (Per Week)	Medium/High-Mercury Fish (Per Week)
Adults, Not Pregnant	2–3 servings of low-mercury fish.	Up to 1 serving of medium-mercury fish; high-mercury fish kept to rare occasions.
Pregnant Or Breastfeeding	2–3 servings of low-mercury fish (about 4 oz cooked per serving).	Albacore tuna up to 1 serving; no shark, swordfish, king mackerel, tilefish, marlin, orange roughy or bigeye tuna.
Children 1–3 Years	2 servings of low-mercury fish (about 1 oz cooked per serving).	Medium-mercury fish only occasionally; avoid high-mercury fish.
Children 4–7 Years	2 servings of low-mercury fish (about 2 oz cooked per serving).	Medium-mercury fish only occasionally; avoid high-mercury fish.
Children 8–10 Years	2 servings of low-mercury fish (about 3 oz cooked per serving).	Medium-mercury fish now and then; avoid high-mercury fish.
Children 11+ Years	2 servings of low-mercury fish (about 4 oz cooked per serving).	Similar to adults; keep high-mercury fish off regular rotation.

Practical Tips To Cut Mercury From Your Plate

Once you know which fish have more mercury, daily choices become much easier. These simple steps help you shape a seafood pattern that keeps benefits high and mercury intake modest.

Vary The Types Of Fish You Eat

Instead of relying on one species every week, rotate through a set of low-mercury fish. For example, you might serve salmon on Monday, shrimp pasta later in the week, and a cod stew on the weekend. A varied mix helps spread any exposure across different sources and keeps meals interesting.

Check Local Fish Advisories

If you catch your own fish or receive fish from friends and family who fish in local waters, check regional advisories. Some lakes and rivers have higher mercury levels than others. The EPA hosts tools that point to state and regional notices so you can match your catch to safe serving patterns.

Watch Portion Sizes

Serving size matters as much as frequency. A serving in many charts is measured after cooking and is smaller than many restaurant plates. At home, a portion about the size of the palm of your hand is close to 4 ounces of cooked fish for an adult. For younger children, serve smaller pieces matched to their age and appetite.

Pay Extra Attention During Pregnancy And Early Childhood

People who are pregnant, might soon become pregnant, or are breastfeeding, along with families feeding toddlers and school-age children, should pay close attention to fish type and frequency. For these groups, the safest path is to pick from the low-mercury “best choices” list and treat higher mercury species as off limits for now.

If you already eat a lot of high-mercury fish and are worried about past exposure, talk with your doctor or midwife. They can review your pattern, consider blood tests if needed, and give advice matched to your health history.

Balance Mercury Risks With Seafood Benefits

Fish bring protein, omega-3 fats and other nutrients that support heart and brain health across life. The goal is not to quit seafood but to choose it with a bit of strategy. By leaning on low-mercury species, keeping medium-mercury fish in rotation but not on repeat, and saving high-mercury fish for rare occasions, you can answer the question “what fish has mercury in them?” with confidence and still enjoy seafood on a regular basis.