Oily fish, also called fatty fish, are fish with higher levels of fat in their flesh. That fat carries EPA and DHA, the long-chain omega-3 fatty acids most strongly associated with fish. Common examples include salmon, sardines, herring, anchovies, trout, mackerel, tuna, and some shellfish such as oysters and mussels.
These fish are valuable because they combine omega-3 fats with protein, vitamin D, vitamin B12, iodine, selenium, and other minerals. The strongest nutrition advice is food-based: eat fish as part of a balanced pattern rather than relying only on fish oil capsules.
Heart Health
The American Heart Association recommends eating two servings of fish per week, particularly fatty fish. A serving for adults is generally about 3.5 to 4 ounces cooked. This pattern can support heart health, especially when fish replaces processed meats, fried foods, or meals high in saturated fat.
EPA and DHA may help lower triglycerides, support normal heart rhythm, and influence inflammation and blood vessel function. Fish is not a cure for heart disease, but oily fish fits well within heart-conscious eating patterns that also emphasize vegetables, fruits, legumes, whole grains, nuts, and unsaturated fats.
Eye And Brain Health
DHA is an important structural fat in the retina and brain, which is one reason oily fish has been studied for vision and cognitive health. A 2008 European study reported that people who ate oily fish at least once a week were less likely to have wet age-related macular degeneration than those who ate it less often.
That finding is consistent with broader interest in omega-3 fats and eye health, but it should be read as association rather than a guarantee. Eye health also depends on age, genetics, smoking status, blood pressure, sunlight exposure, diabetes, and regular eye care.
Best Choices
Small oily fish are often excellent choices. Sardines, anchovies, herring, trout, and salmon tend to provide omega-3 fats while generally being lower in mercury than large predatory fish. Canned sardines and salmon can also provide calcium when the soft bones are eaten.
Tuna varies. Light canned tuna is generally lower in mercury than albacore or bigeye tuna, while fresh large tuna can be higher. King mackerel is high in mercury and is not the same as Atlantic or Pacific chub mackerel, which are commonly listed among better choices.
Mercury And Safety
Fish can contain methylmercury and other environmental contaminants, so variety and species choice matter. FDA and EPA advice encourages people who are pregnant, might become pregnant, breastfeeding, or feeding children to choose lower-mercury fish and follow serving guidance.
High-mercury fish such as shark, swordfish, king mackerel, marlin, orange roughy, bigeye tuna, and tilefish are best avoided by those higher-risk groups. Local fish advisories are important for recreationally caught fish, since mercury and contaminant levels vary by waterway.
Cooking Oily Fish
Oily fish works well with simple cooking methods: roasting, grilling, poaching, broiling, baking, or pan-searing. Strong flavors like lemon, dill, parsley, garlic, mustard, capers, tomatoes, olives, ginger, soy sauce, miso, chili, and vinegar balance the richness.
For a quick meal, pair salmon or sardines with whole grains and vegetables, as in the image above. Canned fish can become toast, salad, pasta, rice bowls, fish cakes, or a spread with yogurt, herbs, and lemon. Avoid making fried fish the default, since frying can add less desirable fats and calories.
Supplements Versus Fish
Fish oil supplements can be useful in specific medical situations, especially for treating high triglycerides under medical supervision. For general wellness, supplements do not fully replace eating fish because whole fish provides protein, vitamins, minerals, and a food matrix that capsules do not.
People taking blood-thinning medications, preparing for surgery, managing heart rhythm issues, or using high-dose omega-3 products should talk with a healthcare professional. Prescription omega-3 products are different from over-the-counter supplements.
Final Note
Oily fish is one of the most efficient food sources of EPA and DHA omega-3 fats. Two servings a week of lower-mercury fatty fish can support a healthy eating pattern, especially when paired with vegetables, whole grains, legumes, and unsaturated fats. Choose a variety of fish, respect mercury guidance, and keep preparation simple.