10 Fish You Should Think Twice About Ordering at a Restaurant
There’s something undeniably appealing about ordering seafood at a restaurant.
A beautifully grilled fillet, a plate of crispy fried fish, or a bowl of fresh seafood can feel like the perfect choice when you're dining out. Fish is often associated with healthy eating, high-quality protein, and beneficial nutrients, so it can seem like an obvious alternative to heavier dishes.
Many people even have a favorite fish they order without thinking twice.
Maybe it's salmon.
Perhaps you prefer tuna, swordfish, sea bass, snapper, grouper, or another popular option.
But choosing seafood at a restaurant isn't always as simple as picking whatever sounds best on the menu.
Certain types of fish can come with questions about mercury, sustainability, freshness, sourcing, preparation, and even labeling. That doesn't mean these fish are automatically unsafe or that you should never eat them. In many cases, the issue is simply that consumers should understand what they're ordering and how frequently they eat it.
Large predatory fish, for example, can naturally accumulate more mercury than smaller fish. Some popular species can also be under pressure from overfishing, while others are occasionally substituted or mislabeled in the seafood industry.
And restaurant preparation adds another variable.
A fish that is naturally nutritious can become a much heavier meal when it is deep-fried, covered in a rich sauce, or served alongside large portions of butter and refined carbohydrates.
So, before your next seafood dinner, here are 10 types of fish you may want to think twice about ordering, along with what to consider before making your choice.
1. Swordfish
Swordfish is a classic restaurant choice.
Its thick, meaty texture makes it feel almost like a steak, and it holds up beautifully to grilling, broiling, and roasting. A well-prepared swordfish steak with lemon, herbs, and vegetables can be delicious.
However, swordfish is also one of the species that deserves particular attention because it tends to contain relatively high levels of mercury.
Mercury can accumulate in fish through a process known as bioaccumulation. Large predatory fish are especially likely to contain more mercury because they live longer and consume other fish over time.
That doesn't mean a healthy adult has to avoid swordfish completely. Fish can be an important part of a balanced diet, and seafood provides valuable nutrients.
The concern is more about frequency and who is eating it.
People who are pregnant or breastfeeding, as well as parents choosing seafood for young children, should pay particular attention to mercury guidance.
If swordfish is one of your favorites, consider treating it as an occasional choice rather than your standard seafood order.
When available, lower-mercury options can give you many of the nutritional benefits of seafood with less exposure.
2. King Mackerel
Mackerel can be confusing because not all types of mackerel have the same nutritional and mercury profile.
Some varieties are excellent seafood choices, while king mackerel is a species that deserves more caution because it can contain high levels of mercury.
It is a large predatory fish, which helps explain why mercury can accumulate in its tissues.
This is particularly relevant for people who eat seafood frequently.
The mistake is assuming that because a fish is generally considered nutritious, every variety is equally suitable for frequent consumption.
When ordering mackerel, don't be afraid to ask what type it is.
If the restaurant simply lists "mackerel" without specifying the species, clarification can be useful.
Smaller mackerel species may be very different from king mackerel in terms of mercury exposure.
For people who enjoy the rich, oily flavor of mackerel, there are often alternatives that provide beneficial omega-3 fats without the same level of concern.
3. Shark
Shark may not be the first thing everyone thinks of when ordering seafood, but it appears on menus in some restaurants and is eaten in various parts of the world.
Like swordfish and king mackerel, shark is a large predatory fish.
That matters because large, long-lived predators tend to accumulate more mercury.
Some shark species can therefore contain levels that make them poor choices for frequent consumption, particularly for vulnerable groups.
There is also an environmental consideration.
Many shark populations have experienced significant pressure from fishing, and sharks play important roles in marine ecosystems.
Their slow growth and relatively low reproductive rates can make population recovery difficult when fishing pressure is high.
So if shark appears on a menu, there are two questions worth considering:
How much mercury might it contain?
And where did it come from?
If you're simply looking for a nutritious seafood meal, there are usually plenty of alternatives.
4. Orange Roughy
Orange roughy has an interesting history.
For years, it was marketed as an appealing white fish with a mild flavor and firm texture. It became popular in restaurants because it was versatile and relatively easy to prepare.
But orange roughy deserves a second thought for two major reasons: mercury and sustainability.
These fish can live for an extraordinarily long time compared with many other commercially harvested species. Because mercury accumulates over a fish's lifetime, long-lived species can contain relatively high concentrations.
Their slow growth and late maturity also create sustainability challenges.
A fish that takes many years to reach reproductive maturity can be difficult to harvest sustainably if fishing pressure is intense.
That doesn't mean every serving of orange roughy is automatically problematic.
But it does mean that it isn't necessarily the best default seafood choice if you're trying to balance nutrition, mercury exposure, and environmental responsibility.
When ordering an unfamiliar white fish, ask what species you're actually getting.
You may discover there is a better alternative available.
5. Tilefish
Tilefish is another seafood choice that deserves caution, particularly depending on where it was caught.
Some tilefish populations are known for elevated mercury levels, and mercury concentrations can vary according to the species and geographic location.
This is a perfect example of why the word "fish" alone doesn't tell you everything you need to know.
Different species live different lives.
They occupy different parts of the ocean.
They eat different foods.
They live for different lengths of time.
And they can accumulate contaminants at different rates.
If you're pregnant, planning a pregnancy, breastfeeding, or choosing fish for a child, paying attention to official seafood recommendations is especially important.
For everyone else, the key is variety.
Rather than repeatedly ordering the same higher-mercury species, consider rotating through seafood choices that are generally lower in mercury.
6. Bigeye Tuna
Tuna is one of the most popular seafood choices in restaurants.
It's found in sushi bars, steakhouse menus, salads, sandwiches, and countless other dishes.
But "tuna" isn't one single fish.
Different tuna species have different characteristics, and bigeye tuna is one variety that deserves particular attention because of its mercury content.
This is especially relevant when eating tuna frequently.
A person who occasionally enjoys tuna is in a very different situation from someone who eats tuna several times a week.
Preparation also matters.
Raw tuna dishes such as sashimi and tuna tartare may be delicious, but raw seafood carries additional food-safety considerations. Restaurants that specialize in raw seafood should follow appropriate handling and storage practices, but consumers should still understand that raw fish isn't risk-free.
When ordering tuna, ask what species you're being served when that information isn't obvious.
If you're trying to minimize mercury exposure, consider choosing lower-mercury seafood more often.
7. Imported or Poorly Identified Sea Bass
"Sea bass" sounds straightforward, but restaurant menus can sometimes make seafood identification surprisingly complicated.
The term can refer to different species depending on the restaurant, country, or supplier.
One well-known example is Chilean sea bass, which is actually Patagonian toothfish.
It has become famous for its buttery texture and rich flavor, making it a popular upscale restaurant choice.
But its history includes significant sustainability concerns, although responsible fisheries and certification programs have changed the situation for some sources.
This is why sourcing matters.
Instead of assuming that every fish labeled "sea bass" is identical, ask the restaurant where it comes from and what species it is.
A reputable restaurant should generally be able to provide basic information about its seafood.
If the staff cannot explain what you're ordering, that may be a reason to choose something else.
8. Grouper
Grouper is prized for its mild flavor and firm, flaky texture.
It is particularly popular in coastal restaurants and is often grilled, blackened, fried, or served with sauces.
But grouper can present two separate concerns.
The first is sustainability.
Certain grouper populations have experienced fishing pressure, and the sustainability of a particular dish depends heavily on the species and where it was caught.
The second issue is food safety.
Some reef-associated fish, including certain grouper species, can be associated with ciguatera, a naturally occurring toxin that can accumulate in larger reef fish.
Ciguatera isn't destroyed by normal cooking.
Importantly, this doesn't mean that grouper from a reputable restaurant is automatically dangerous. The risk varies significantly by species and location, and commercial seafood systems have measures intended to reduce these risks.
Still, asking about the source can be worthwhile, particularly when traveling or eating unfamiliar reef fish.
9. Red Snapper
Red snapper is another restaurant favorite.
It has a delicate flavor, firm texture, and versatility that makes it suitable for grilling, baking, frying, or pan-searing.
But there is an issue consumers don't always consider:
Is it actually red snapper?
Seafood mislabeling has been a longstanding concern in the food industry. Some species can look similar once filleted, making substitution easier.
The name on a menu doesn't always tell you everything about the fish's actual identity.
A reputable restaurant that takes seafood seriously should be able to explain where its fish comes from and, when appropriate, what species it is.
Sourcing also matters from an environmental perspective.
Different fisheries can have very different sustainability profiles.
So if red snapper is on the menu, there's nothing inherently wrong with ordering it. But if sustainability or authenticity matters to you, it's reasonable to ask a few questions.
10. Fried Fish
This final category is slightly different.
The issue isn't necessarily the fish itself.
It's what the restaurant does to it.
Fish can be an excellent source of protein and can provide important nutrients, including omega-3 fatty acids in certain species.
But deep-frying changes the nutritional profile of the overall meal.
A delicate fish fillet can become a much heavier dish when covered in batter, fried in oil, and served with fries, creamy sauces, and large portions.
Again, this doesn't mean fried fish should never be eaten.
Food doesn't have to be perfectly healthy to be enjoyable.
But if you're ordering seafood because you want a lighter or more nutritious restaurant meal, grilled, baked, steamed, or broiled fish may better match that goal.
Pay attention to the entire plate, not just the fish.
A grilled fish dish served with vegetables can be very different nutritionally from a battered fish platter with fries and creamy dipping sauce.
The Bigger Issue: Variety Matters
Perhaps the biggest lesson isn't that you should create a blacklist of fish you can never order.
It's that variety matters.
Eating the same species repeatedly can increase your exposure to whatever contaminants are more common in that particular fish.
Rotating between different types of seafood allows you to enjoy the nutritional benefits of fish while avoiding excessive reliance on one species.
You can also consider choosing smaller fish and species that are generally recognized as lower in mercury.
Options such as salmon, sardines, anchovies, trout, pollock, and some varieties of shrimp can often fit into a varied seafood diet, depending on individual circumstances and local guidance.
The important thing is to look beyond the headline.
"Fish is healthy" is too broad.
"All fish is dangerous" is also wrong.
The reality is more nuanced.
Different species have different nutritional profiles, mercury levels, sustainability concerns, and food-safety considerations.
Don't Be Afraid to Ask Questions
One of the easiest ways to make better choices at a restaurant is simply to ask.
You don't need to interrogate the server.
A few basic questions can provide useful information:
What species is this?
Where is it sourced from?
Is it wild-caught or farmed?
How is it prepared?
Is the fish previously frozen?
For raw seafood, you may also want to know how it is handled and whether the restaurant specializes in serving raw fish.
Good restaurants should understand these questions.
In fact, knowledgeable staff will often appreciate customers who care about what they're eating.
Freshness Matters Too
No matter which species you choose, freshness and proper handling are critical.
Seafood is highly perishable.
A fish can be nutritionally excellent and still become a food-safety problem if it isn't stored, transported, or prepared properly.
When eating at a restaurant, pay attention to obvious warning signs.
Strong unpleasant odors, unusual textures, or food that appears improperly handled can justify speaking with staff or choosing another dish.
However, remember that not every unusual smell indicates spoiled seafood. Certain varieties naturally have stronger aromas, and preparation methods can influence smell as well.
When in doubt, ask.
The Bottom Line
Ordering seafood at a restaurant doesn't have to be complicated.
You don't need to fear every fish on the menu.
And you certainly don't need to give up seafood altogether.
The smarter approach is to understand that different fish come with different considerations.
Swordfish, king mackerel, shark, orange roughy, tilefish, bigeye tuna, certain sea bass, grouper, and some other large or long-lived species can warrant extra attention because of mercury, sustainability, sourcing, or other concerns.
Meanwhile, preparation can turn an otherwise nutritious fish into a much heavier meal.
The best strategy is simple:
Choose variety.
Pay attention to sourcing.
Know which fish are higher in mercury.
Consider how the fish is prepared.
Be especially careful when choosing seafood for pregnant people and young children.
And don't be afraid to ask the restaurant what you're actually being served.
The next time you open a seafood menu, you don't have to panic when you see one of these fish.
Instead, pause for a moment.
Think about how often you've eaten that species recently.
Consider who is eating it.
Ask where it came from.
And look at the entire meal—not just the fish itself.
After all, eating seafood can be a delicious and nutritious part of a balanced diet.
The goal isn't to eliminate every potentially concerning choice.
It's to make informed choices, enjoy plenty of variety, and know what is actually on your plate.
