6 Fish You May Want to Avoid at Restaurants — And Better Choices to Order Instead

Ordering fish at a restaurant can feel like one of the healthiest choices on the menu. Fish can provide high-quality protein, omega-3 fatty acids, vitamins, and important minerals.

But the type of fish, where it comes from, and how it was caught or farmed can make a big difference.

Some species tend to contain more mercury, while others may raise sustainability concerns depending on their source. That doesn’t necessarily mean you must never eat them, but knowing what you’re ordering can help you make a more informed choice.

Here are six fish worth thinking twice about—and some alternatives to consider.

1. Shark

Shark is served in some restaurants around the world, but it’s generally not an ideal everyday seafood choice.

Why reconsider it

Sharks are large, long-lived predators. Because they’re high on the food chain, mercury can accumulate in their bodies over time.

Many shark populations are also vulnerable to overfishing because sharks generally grow and reproduce slowly.

Try instead

Consider salmon, sardines, trout, or other responsibly sourced lower-mercury fish.

These can provide plenty of flavor and nutrients without the same mercury concerns associated with large predatory species.

2. Swordfish

Swordfish has a firm texture that makes it popular for grilling, but it’s another large predatory fish known for relatively high mercury levels.

Why reconsider it

Mercury exposure is particularly important to consider for children and people who are pregnant, breastfeeding, or may become pregnant.

For other adults, local health authorities may provide recommendations about appropriate serving frequency.

Try instead

For something substantial enough to grill, consider salmon or trout, depending on what’s available and responsibly sourced.

3. King Mackerel

Here’s where the name matters.

Mackerel as a category isn’t necessarily something to avoid. In fact, several types can be nutritious choices.

King mackerel, however, is a large predatory species that can contain relatively high concentrations of mercury.

Try instead

Look for smaller mackerel species or consider sardines.

Smaller oily fish can be excellent sources of omega-3 fatty acids while generally accumulating less mercury than large predatory fish.

4. Orange Roughy

Orange roughy became a popular restaurant fish because of its mild flavor, but there are reasons to be selective about ordering it.

Why reconsider it

Orange roughy is an exceptionally slow-growing, long-lived deep-sea fish. Those biological characteristics can make populations particularly vulnerable to heavy fishing pressure.

Its long lifespan can also contribute to contaminant accumulation.

Try instead

Ask your server about a responsibly sourced local white fish.

The best alternative will depend heavily on where you’re dining and what’s sustainably available in that region.

5. Marlin

Like shark and swordfish, marlin is a large ocean predator.

Why reconsider it

Large predatory fish tend to accumulate more mercury than smaller species lower on the food chain.

There may also be conservation concerns surrounding particular marlin populations and fishing methods.

Try instead

Consider salmon, trout, sardines, or another smaller responsibly sourced species.

6. Certain Types of Tuna

This one requires some nuance because not all tuna is the same.

Different tuna species can have very different mercury levels and sustainability profiles.

Large tuna species generally accumulate more mercury over their lifetimes than smaller fish. Sustainability also depends on the species, location, and fishing method.

That means simply seeing “tuna” on a restaurant menu doesn’t provide enough information to judge it.

What to ask

You can simply ask:

“What type of tuna is this, and where was it sourced?”

A restaurant that pays close attention to its seafood supply may be able to provide that information.

The Important Truth: A Species Isn’t Automatically “Good” or “Bad”

Seafood sustainability can be complicated.

The same species may be a responsible choice when caught in one location using one method and a poor choice when sourced somewhere else.

That’s why broad lists of “fish you should NEVER eat” can be misleading.

Instead, consider three questions:

What species is it?

Knowing the exact species helps you understand potential mercury and conservation concerns.

Where did it come from?

Different fisheries and farms can have dramatically different environmental practices.

How was it caught or raised?

Fishing and aquaculture methods influence habitat damage, accidental catch of other animals, pollution, and sustainability.

Better Seafood Choices to Look For

Although sourcing still matters, several types of seafood are often worth considering.

Sardines

These small oily fish provide protein and omega-3 fatty acids. Because they’re relatively low on the food chain, they generally contain less mercury than large predators.

Salmon

Salmon is rich in omega-3 fatty acids and widely available, although environmental considerations vary between wild fisheries and different farming systems.

Check the source when possible.

Trout

Trout can be another nutritious option, particularly when responsibly farmed or caught.

Mussels

Farmed mussels can be an interesting sustainable seafood option because they require little additional feed and filter naturally occurring nutrients from the water.

Oysters

Responsibly farmed oysters share some of the environmental advantages of other farmed shellfish.

What About Mercury?

Mercury occurs naturally in the environment but can also enter ecosystems through human activities.

In waterways, microorganisms can convert it into methylmercury, which accumulates in aquatic organisms.

Small fish absorb relatively small amounts. Larger fish eat many smaller fish, and predators may continue accumulating mercury throughout their lives.

That’s why some of the largest, longest-lived predators tend to have higher concentrations.

Who Should Be Especially Careful?

Seafood provides valuable nutrients, so the goal isn’t necessarily to eliminate fish.

However, children and people who are pregnant, breastfeeding, or may become pregnant should pay particular attention to official recommendations regarding mercury.

Guidance differs by country, so follow recommendations from your national or local health authority.

Don’t Forget Food Safety

The species isn’t the only thing that matters when ordering seafood.

Proper refrigeration, preparation, and cooking are also important.

Raw or undercooked seafood carries a greater risk of foodborne illness. People who are pregnant, very young, older, or immunocompromised may need to take additional precautions.

When in doubt, choose thoroughly cooked seafood from a reputable restaurant.

A Simple Rule When Reading the Menu

You don’t need to memorize dozens of species.

A useful starting principle is:

Favor smaller, responsibly sourced seafood and be more cautious with large, long-lived predatory fish.

And when the menu doesn’t tell you where the seafood comes from, ask.

A simple question about the species and source can tell you far more than a dramatic online list of “good” and “bad” fish.

The Bottom Line

Fish can absolutely be part of a nutritious diet.

The goal isn’t to become afraid of seafood—it’s to become a more informed diner.

Large predators such as shark, swordfish, king mackerel, marlin, and some tuna species deserve extra consideration because of mercury levels. Other fish, including orange roughy, can raise sustainability concerns.

Meanwhile, choices such as sardines, responsibly sourced salmon and trout, mussels, and oysters can often be excellent alternatives.

So the next time you’re staring at the seafood section of a restaurant menu, don’t hesitate to ask one simple question:

“Where does this fish come from?”

The answer can help you choose a meal that’s good for you—and a little gentler on the oceans too.