Fish is often celebrated as a smart choice for a balanced diet – it’s naturally high in protein, rich in omega-3 fatty acids, and can support both heart and brain health. However, not all fish are created equal.
While some varieties are genuinely beneficial, others can come with downsides such as higher mercury levels, sustainability concerns, or less-than-ideal farming conditions.
This guide highlights eight fish that are generally positive additions to your menu – and eight you may want to think twice about.
This article is for general informational purposes only. Nutritional content and sustainability standards vary by species and region. Always follow official food safety guidance and check local recommendations regarding seafood consumption, particularly for pregnant people, young children, and those with specific medical conditions.
1. Sardines
Sardines might be small, but they pack an almighty nutritional punch! These little swimmers are absolutely loaded with omega-3 fatty acids, vitamin D, and calcium (especially when you eat the soft, edible bones).
Unlike larger fish, sardines sit low on the food chain, meaning they contain virtually no mercury or other harmful contaminants. They're also one of the most sustainable seafood choices available, with healthy population numbers that aren't threatened by overfishing.
Whether tinned or fresh, sardines make a brilliant addition to salads, pasta dishes, or simply enjoyed on toast with a squeeze of lemon. Your heart, brain, and the planet will thank you!
2. Wild-Caught Salmon
Nothing beats wild-caught salmon for pure nutritional value. The vibrant pink flesh reveals its rich astaxanthin content – a powerful antioxidant that farmed varieties often lack. Each delicious bite delivers omega-3 fatty acids that support heart and brain health.
Alaska's strictly managed fisheries make Pacific salmon (like sockeye, coho, and king) particularly sustainable choices. The fish swim freely in clean waters, developing stronger flavour profiles than their farmed counterparts.
While it costs more than farmed options, the superior taste and nutritional benefits make it worth the splurge for occasional meals. Look for MSC-certified wild salmon to ensure you're getting the genuine article from responsibly managed sources.
3. Rainbow Trout
Rainbow trout delivers that classic salmon-like experience without the hefty price tag or environmental concerns. Raised primarily in freshwater tanks with recirculating systems, farmed rainbow trout represents one of aquaculture's genuine success stories.
The mild, slightly nutty flavour makes it perfect for those who find salmon a bit too intense. Each serving provides an excellent source of protein, B vitamins, and those all-important omega-3s that keep our brains and hearts ticking along nicely.
Cooking couldn't be simpler – just a quick pan-fry with herbs and butter creates a delicious meal in minutes. The firm, pink flesh holds together beautifully whether baked, grilled, or smoked.
4. Mackerel
Mackerel deserves far more love than it typically receives in British kitchens. This oily fish delivers more omega-3 fatty acids per gram than virtually any other seafood – at a fraction of the price of salmon or tuna. The distinctive bold flavour stands up beautifully to strong seasonings and smoking techniques.
Atlantic mackerel from UK waters represents one of our most sustainable fish choices, with healthy populations that reproduce quickly. The distinctive blue-green tiger stripes on its back make it easy to identify at the fishmonger's.
For the freshest experience, look for clear eyes and metallic skin. Grilled whole with herbs or pickled in vinegar (as in Spanish escabeche), mackerel makes for spectacular eating that supports both local fisheries and your health.
5. Herring
Herring was once a staple of British diets, and it's high time this nutritional powerhouse made a comeback. Similar to its cousin the sardine, herring delivers exceptional levels of vitamin D (something many Brits lack), omega-3s, and B12 at a remarkably affordable price.
The North Atlantic populations remain healthy and well-managed, making herring one of the most sustainable fish choices available. Its rich, distinctive flavour works beautifully when pickled (as rollmops), smoked (kippers), or simply grilled fresh with a squeeze of lemon.
For the freshest experience, look for bright eyes and metallic skin at your fishmonger. The Scots have long understood herring's value – perhaps it's time the rest of us caught up!
6. Arctic Char
Arctic Char, a cousin of salmon and trout, offers a delightful flavor and numerous health benefits. Its brilliant pinkish-orange flesh is rich in omega-3 fatty acids, which support heart and brain health.
Unlike some other fish, Arctic Char generally comes from sustainable farming, making it an environmentally friendly choice. Its taste is often described as a cross between salmon and trout, with a delicate and buttery texture.
Not only does it taste great, but Arctic Char is also packed with protein, vitamin D, and selenium. This makes it a highly nutritious addition to your diet.
7. Anchovies
Anchovies may be small, but they pack a punch with their rich omega-3 content, benefiting heart health and reducing inflammation. With a unique, bold flavor, these tiny fish are more than just a pizza topping. Their calcium content supports bone health, making them a nutritious choice for various diets.
In Mediterranean dishes, anchovies add depth and complexity, harmonizing with tomatoes and olives. Sustainable and low in mercury, they provide a responsible seafood option. Consider adding anchovies to your meals for a savory and nutritious boost that will delight your palate and nourish your body.
8. Mussels
Mussels might not technically be fish, but they certainly deserve a spot on your seafood rotation. These brilliant bivalves actually improve water quality as they grow, filtering gallons of water daily and removing excess nutrients from their environment.
Nutritionally, they're absolute powerhouses – packed with protein, B12, iron, zinc, and selenium, all while remaining low in calories and fat. Farmed mussels have minimal environmental impact, requiring no feed or antibiotics to thrive.
The classic moules marinière (mussels steamed with white wine, garlic and herbs) transforms these humble shellfish into a restaurant-worthy feast at home. For about a fiver per kilo, you'll struggle to find a more affordable, sustainable protein source anywhere.
9. Swordfish
Swordfish steaks might look impressive on your plate, but this predator comes with significant health concerns. As a large, long-lived predatory fish, swordfish accumulates mercury at levels that make regular consumption potentially risky, especially for pregnant women and children.
Beyond the toxicity concerns, swordfish populations face immense pressure from overfishing. Many swordfish are caught using longline methods that result in substantial bycatch of sea turtles, sharks, and other marine life.
While the firm, meaty texture appeals to many, the environmental and health impacts simply outweigh the benefits. If you're craving a substantial fish steak, consider more sustainable alternatives like mahi-mahi or thick-cut farmed sturgeon instead.
10. Farmed Atlantic Salmon
Those bright pink fillets dominating supermarket seafood counters aren't quite the nutritional superstars they appear to be. Farmed Atlantic salmon contains significantly fewer omega-3s and more fat than wild varieties. The vibrant colour often comes from added pigments rather than naturally occurring astaxanthin.
Conventional salmon farms can create serious environmental issues, including pollution from concentrated waste, spread of parasites to wild populations, and the use of antibiotics. The feed typically contains wild-caught fish, creating pressure on other marine ecosystems.
If salmon is on your menu, look for responsibly farmed options certified by the Aquaculture Stewardship Council or, better yet, opt for wild-caught Pacific varieties when your budget allows. Your body and the environment deserve better than standard farmed Atlantic.
11. Bluefin Tuna
Bluefin tuna's buttery texture and rich flavour have made it prized in high-end restaurants, particularly for sushi and sashimi. Unfortunately, this popularity has driven Atlantic bluefin to the brink of extinction, with populations at a fraction of their historic levels.
Beyond the sustainability nightmare, bluefin presents serious health concerns. These massive predators accumulate mercury and other toxins throughout their long lives, potentially harming nervous system development in children and fetuses.
No matter how tempting, bluefin tuna should be firmly off the menu. For tuna flavour without the ethical or health baggage, skipjack (commonly used in tinned tuna) offers a more sustainable alternative with lower mercury levels. Your conscience – and body – will thank you.
12. Pangasius (Basa)
Those suspiciously cheap white fish fillets labelled 'pangasius' or 'basa' in the freezer section come with hidden costs. Primarily farmed in Vietnamese ponds and sections of the Mekong Delta, these catfish are often raised in crowded, polluted conditions with questionable oversight.
Nutritionally, pangasius offers little to write home about. The mild-tasting flesh contains minimal omega-3s and fewer proteins than most other fish. What you're getting is essentially the aquatic equivalent of fast food – cheap, bland, and nutritionally underwhelming.
Farming practices frequently involve heavy antibiotic use and chemical treatments to control disease in overcrowded ponds. For white fish, you're much better off with locally caught options like haddock, coley, or pollock.
13. Orange Roughy
Orange roughy might appear occasionally on restaurant menus or in frozen sections, but this deep-sea dweller represents a textbook case of unsustainable fishing. These remarkable fish can live up to 100 years and don't reproduce until they're 20-30 years old, making their populations extremely vulnerable to overfishing.
The fishing methods used to catch orange roughy – primarily deep-sea bottom trawling – cause catastrophic damage to seafloor habitats that may take centuries to recover, if ever. Many populations have already collapsed due to intensive harvesting.
From a health perspective, these long-lived fish accumulate significant levels of mercury over their extended lifespans. With so many sustainable white fish alternatives available, there's simply no justification for choosing orange roughy.
14. Imported Shrimp
Those cheap frozen prawns from Asia and Latin America come with a devastating environmental price tag. Tropical shrimp farming has destroyed millions of acres of mangrove forests – crucial coastal ecosystems that protect shorelines and serve as nurseries for countless marine species.
Intensive farming operations frequently use antibiotics and chemicals banned in the UK and EU. Wild-caught tropical shrimp isn't much better, often harvested using methods that result in up to 15 pounds of bycatch (unwanted sea creatures) for every pound of shrimp.
If you're craving prawns, look for MSC-certified wild options from cold waters or responsibly farmed varieties from Europe or North America. Better yet, try UK-caught brown shrimp – tiny but packed with flavour and far more sustainable.
15. Tilapia
Tilapia, often found on restaurant menus, might not be the healthiest choice. It is commonly farmed, sometimes in overcrowded conditions, leading to concerns about pollutants and antibiotics.
It's low in omega-3 fatty acids compared to other fish, which diminishes its heart health benefits. Additionally, the farming practices can lead to higher levels of omega-6 fatty acids, which may contribute to inflammation.
While affordable and mild in flavor, the health trade-offs might not be worth it. Opting for wild-caught alternatives can provide better nutritional benefits without the environmental downsides.
16. Tilefish
Tilefish, known for their vibrant colors, are a feast for the eyes but may not be the best choice for your health. This species often contains high mercury levels, posing serious risks, especially for pregnant women and children. Despite its appealing taste and firm texture, the potential health hazards overshadow its culinary charm.
Regulations exist to limit tilefish consumption, reflecting the growing awareness of its mercury content. While beautiful and tempting, this fish is best admired from a distance. Consider other seafood options that offer flavor without the health risks associated with high mercury levels.
