Top 10 Healthy Fish to Eat

Salmon, tuna, sardines and mackerel are considered the healthiest fish to eat. Rich in protein and omega-3s, they keep your brain and heart functioning optimally. What you may not know is that anchovies, cod, oysters, crab and other fish are just as beneficial.

More than 32,000 fish species exist, and each has distinct characteristics. Canned tuna and wild-caught salmon are not your only options. Bonitos, haddocks, herring and tilapia all have their place in a balanced diet.

Nutritionists worldwide recommend eating at least two servings of fish per week — and for good reason. Regular fish consumption has been linked to a healthier brain, improved cardiovascular health and even weight loss. For example, a May 2013 review published in the ​Indian Journal of Endocrinology and Metabolism​ emphasizes its cardiac benefits.

As the researchers note, fish may help improve blood lipids and protect against heart disease due to their high levels of omega-3s. DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), the omega-3 fatty acids in salmon, herring, tuna and other fatty fish, may reduce triglycerides and cholesterol levels, decrease blood pressure and prevent plaque buildup.

These nutrients also fight inflammation and may help alleviate the symptoms associated with Crohn's disease, lupus, arthritis and other inflammatory disorders.

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If you're trying to slim down, fill up on fish and seafood. The omega-3s in fish may improve insulin sensitivity and raise adiponectin levels, making weight loss easier, according to the ​Indian Journal of Endocrinology and Metabolism​ review. Adiponectin, a protein secreted by white adipose tissue, protects against insulin resistance, a risk factor for obesity. This compound regulates lipid metabolism, glycemic control and other processes that influence your weight.

However, some types of fish are healthier than others. Additionally, not all fish are edible.

The Food and Drug Administration (FDA) recommends eating salmon, sardines, oysters, white fish, cod and herring two to three times per week. These fish varieties are the lowest in mercury. Others, such as albacore tuna, halibut, carp and tilefish from the Atlantic have moderate mercury levels, so try not to exceed one serving per week. Shark, king mackerel, tilefish from the Gulf of Mexico and bigeye tuna may not be safe due to their high mercury content.

So, what's the best fish to eat for health? Take this list with you the next time you go shopping.

With 28 grams of protein per serving (3 to 4 ounces), wild-caught salmon is a powerhouse of nutrition. It has just 200 calories and provides large amounts of magnesium, iron, potassium and vitamin B12. In fact, a single serving delivers 140 percent of the daily recommended vitamin B12 intake.

The human body needs vitamin B12 to make DNA and red blood cells, maintain normal brain function and fight neurological disorders. Salmon also boasts 2.5 grams of heart-healthy, omega-3s as well the vitamins A, B1, B3 and B5. Potassium, one of the most abundant nutrients in this fish, regulates blood pressure and fluid balance.

Smoked salmon is healthy too — just make sure you don't go overboard. This delicacy may raise your blood pressure due to its high sodium content. Too much salt may also lead to water retention and cause the numbers of the scale to go up. That's the last thing you want when you're on a diet. Stick to the recommended serving size, which is about 1.5 ounces of smoked salmon.

Sardines are higher in calories than most types of fish, but they pack a hefty nutritional punch. One serving of canned sardines (3 to 4 ounces) has 191 calories, 22.7 grams of protein and 10.5 grams of fat. What makes these tiny fish stand out is their high calcium content. A single can provides nearly one-third of the daily recommended calcium intake.

​Read more:​ Are Canned Sardines Bad for You?

But that's not all. Sardines also boast a whopping 343 percent of the daily recommended allowance of vitamin B12. They are also rich in vitamin D, a nutrient that supports calcium absorption, immune function and bone growth.

Canned sardines may keep your heart healthy, according to a study cited by the experts at Harvard T.H. Chan School of Public Health. Researchers have found that eating one to two servings of fatty fish per week may lower the risk of cardiovascular death by up to 36 percent. Salmon, sardines and mackerel appear to be particularly beneficial.

Atlantic mackerel is touted as one of the healthiest fish due to its high fat content. It provides 15.1 grams of fat, including 1.1 grams of omega-3s per serving (3 ounces). You will also get more than 20 grams of quality protein and 223 calories.

Like other fatty fish, mackerel is rich in vitamin A, vitamin B12, selenium and magnesium. Selenium, one of its key nutrients, supports the formation of antioxidant enzymes and protects your cells from the harmful effects of toxins and heavy metals. This mineral also promotes cardiovascular health, keeps your immune system strong and regulates the metabolism of thyroid hormones, according to a review published in the journal ​Antioxidants & Redox Signaling​ in April 2012.

Just make sure you avoid Spanish mackerel, warns the FDA. Its mercury levels are about nine times higher than those of Atlantic mackerel and four times higher than mercury concentrations in sardines. King mackerel isn't safer, either.

Fatty fish are typically high in calories. If you're looking for a diet-friendly option, canned light tuna will do the trick. One serving (3 ounces) has fewer than 100 calories and over 21 grams of lean protein. It's also a good source of iron, potassium, zinc and vitamin B12.

Light tuna is about three times lower in mercury than canned white tuna, reports the Environmental Defense Fund. The downside is that it also has lower levels of omega-3s compared to salmon, sardines and other fatty fish. One serving of canned light tuna contains just 248 milligrams of heart-healthy fats, while sardines boast more than 1 gram of omega-3 fatty acids per serving.

However, this doesn't mean that light tuna is inferior to other fish varieties. On the contrary, it's an excellent source of protein, vitamin D, vitamin K and B vitamins. Dietary protein fills you up quickly, preserves lean mass and increases your metabolism, which in turn, can facilitate weight loss.

One way to keep your bones healthy is to eat fish more often. This will ensure that you get enough calcium and vitamin D in your diet. Herring, for example, delivers 5 percent of the daily recommended calcium intake and 23 percent of the daily recommended allowance of vitamin D.

Your body needs these nutrients to build strong bones, as the National Osteoporosis Foundation points out. Furthermore, Harvard Health recommends the consumption of calcium and vitamin D from real food, not supplements.

Need one more reason to include herring in your diet? This fish is fairly low in calories and rich in protein.

Each serving provides 173 calories, 19.6 grams of protein and 9.9 grams of fat, including 2 grams of omega-3s. On top of that, it boasts 465 percent of the recommended daily intake of vitamin B12. It goes well in salads and comes with a low price tag, making clean eating easier.

Rainbow trout is ideal for low-carb and low-fat diets. It has slightly more than 140 calories per serving (3 ounces, cooked) and boasts a rich flavor. It also offers 20.2 grams of protein and 6.3 grams of fat, including 837 milligrams of omega-3 fatty acids.

Compared to other fish, trout is significantly higher in vitamin A, vitamin E and vitamin D. One serving supplies more than 80 percent of the daily recommended vitamin D intake and 16 percent of the daily recommended allowance of vitamin E. The latter protects against oxidative stress, supports cellular repair and fights inflammation due to its high antioxidant levels.

The Washington State Department of Health recommends eating two to three servings of trout per week to reap its benefits. This fish is low in mercury and can be safely consumed by children and pregnant women.

Despite their small size, anchovies are chock-full of protein, calcium, iron and vitamin B12. One serving (about five anchovies) has just 42 calories, 2 grams of fat and approximately 6 grams of protein, as well as one-quarter of the daily recommended selenium intake. You'll also get more than 400 milligrams of omega-3 fatty acids.

These small, saltwater fish make a healthy snack between meals. Use them as a substitute for chips, crackers, pretzels and other salty treats. They are significantly more nutritious and lower in calories than most snacks. Plus, sardines contain heart-healthy fats, not trans fats (like potato chips, fries and other traditional snacks).

Watch your portions, though. With over 700 milligrams of sodium per serving, anchovies may increase blood pressure when consumed in large amounts. The American Heart Association recommends 1,500 milligrams to 2,300 milligrams of sodium per day for healthy adults. Five anchovies contain 733 milligrams of sodium — that's about one-third of the maximum daily recommended intake.

Tilapia doesn't contain more protein than salmon or tuna, but it's lower in calories. Each serving (3 ounces) has 111 calories, 22.8 grams of protein and 2.3 grams of fat, including 209 grams of omega-3s. It's a perfect choice for low-calorie and low-fat diets. This fish is also an inexpensive source of protein and can be used in a multitude of recipes.

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A single serving provides 26 percent of the daily recommended intake of niacin, 67 percent of the daily recommended vitamin B12 intake and 86 percent of the daily recommended amount of selenium. Niacin, or vitamin B3, is converted to nicotinamide adenine dinucleotide in the body. This compound contributes to over 400 enzymatic reactions.

Your body needs vitamin B3 for energy metabolism, cell function and blood clotting, points out the U.S. National Library of Medicine. In fact, many people take niacin supplements to reduce bad cholesterol and raise good cholesterol levels. Tilapia is naturally high in niacin and supports overall health.

With only 94 calories per serving (3 ounces), halibut fits into most diets. It's chock-full of protein, potassium, magnesium, vitamin D, niacin and vitamin B6. Calorie per calorie, it offers more protein than beef, poultry and most fish varieties. Each serving provides 19.2 grams of this nutrient.

As mentioned earlier, protein facilitates weight loss and helps maintain lean mass while on a diet. It also plays a key role in muscle growth and repair, appetite control and energy production, as the American Council on Exercise points out.

According to a November 2014 review featured in ​Nutrition & Metabolism​, high-protein diets increase satiety and make it easier to reduce your food intake. A meal rich in protein can fill you up for hours, reducing the urge to snack.

Furthermore, this nutrient takes more energy to digest than fats and carbs. To put it simply, halibut and other protein-rich foods increase calorie burn to a greater extent than mashed potatoes or fruit salad.

Vitamin D and calcium are not the only nutrients required for bone health. Phosphorus is just as important. This mineral supports bone growth and development, maintains bone integrity and protects against bone loss, as reported in a May 2012 review published in ​Pediatric Nephrology​. It's also needed for protein synthesis, energy metabolism, bone mineralization and other biological processes.

Cooked cod delivers 14 percent of the daily recommended phosphorus intake per serving (3 ounces). Salmon and other fish are higher in this mineral, but they also provide more calories. One serving of cod has just 71 calories and 0.2 grams of fat. It's also rich in protein, offering more than 17 grams.

Like most types of fish, cod can be grilled, baked or fried. Incorporate it into your favorite salads, serve it with pickles or leafy greens or experiment with a variety of recipes, such as Greek-style baked cod, spicy cod fritters or grilled cod with salsa. You can use it in fish pies, stews, soups and casseroles. This is one of the healthiest fish to eat, so go ahead and seek new ways to include it in your diet.