The great resources of our oceans, lakes, and rivers have yielded important sustenance in the form of fish for thousands of years. Today there is deep concern that our supply of wild fish is rapidly dwindling. With the advent of high-tech fishing methods, commercial fishermen are catching fish at faster rates than the fish can reproduce.
In order to address this problem, farm-raised fish are becoming more prevalent, with trout and salmon being among the most popular. Aquaculture, the science of breeding and raising fish on fish “farms,” is making a rapidly growing contribution to the supermarket supply of both fresh and saltwater species. But fish farms can have a negative impact on the environment. For example, some salmon farms, which concentrate thousands of fish in pens, may end up dumping vast quantities of waste and chemicals that pollute the water.When farmed fish escape their pens, they can also spread disease to wild fish.
Fish fall into two main categories: freshwater and saltwater.
Freshwater fish are from rivers, lakes, and streams. Some of the more popular types of freshwater fish include lake and rainbow trout, bass, carp, lake perch, catfish, and pike. Freshwater fish tend to have smaller bones and require a bit more care when picking away the minuscule bones, which is often a source of frustration for diners.
Saltwater fish, on the other hand, have larger bones—making them easier to de-bone—and are found in the ocean, gulfs, and seas. The more commonly consumed saltwater fish include salmon, mackerel, haddock, sea bass, cod, flounder, red snapper, swordfish, and tuna. Interestingly enough, saltwater fish are generally no higher in sodium than freshwater fish. Fish have an internal regulatory system that prevents sodium from the water being deposited in their flesh.
Fish are also divided according to their bone and body structure and are either “flat” or “round” fish. Shaped like an oval platter, flatfish, such as flounder, swim horizontally on their sides, along the bottom of the ocean. “Round” fish, such as striped bass, red snapper, and salmon, have thicker, more bullet-shaped bodies, and are more typically “fish” shaped. A round fish is more complicated to fillet than a flatfish, but it yields thicker fillets and meaty steaks, if the fish is reasonably large.
Another distinction among the various kinds of fish is their fat content, with fish being either lean or fatty.
Lean fish (such as sea bass, brook trout, cod, flounder, and red snapper) typically have a mild flavor, making them adaptable to every sort of cuisine, and most of them are similar enough in taste and texture that you can substitute one variety for another.
Fatty fish include some of the more popular fish, such as salmon and tuna. They tend to have a wider distribution of fat, and their flesh is darker, firmer in texture, and has a more distinctive flavor than lean fish.
More than 200 species of fish are caught in American waters alone, and hundreds more are available worldwide. The varieties that appear in markets have shifted over the years. Some traditionally popular species, such as striped bass and swordfish, are relatively scarce (and therefore expensive) due to overfishing and pollution.
Types of Fish
Here's a guide to fresh fish that are available nationwide or in many areas of the country. It's broken into fatty fish (over 5 percent fat by weight) and lean fish (5 percent fat or less).
It’s simplest to think of fish, both from a health standpoint and a cooking standpoint, as lean or fatty. Lower-fat, or lean, fish have less than 5 percent fat by weight. Fatty fish, on the other hand, are more than 5 percent fat by weight.
Only a few so-called fatty fish are truly high in fat, with more than 10 grams of fat per 3 ounces cooked. These fish—which include Boston mackerel, salmon, sardines, and shad—are very rich in the polyunsaturated fatty acids called omega-3s.
Omega-3s make platelets in the blood less likely to stick together and may reduce inflammatory processes in blood vessels and elsewhere. By reducing blood clotting, omega-3s may help lower the chance of a fatal heart attack. Omega-3s in high doses can help decrease levels of triglycerides, the major type of fat that circulates in the blood. They may also make the heart less susceptible to dangerous, sometimes fatal, rhythm abnormalities.
Since this is one instance where fat may help protect the heart, the American Heart Association advises eating at least two servings of fish a week, particularly fatty fish such as salmon and herring. In addition, there’s some research showing that fish oil may help relieve inflammatory symptoms of autoimmune diseases such as rheumatoid arthritis or psoriasis.
Along with heart-healthy fat, fish are very good sources of high-quality protein; they don’t have the artery-clogging saturated fat present in other high-protein foods such as beef, lamb, and pork.
Fish contain “heme” iron, the form of iron that is most readily and easily absorbed by our bodies. Depending on the type, fish also contain significant amounts of B vitamins, especially thiamin, niacin, vitamin B6, and vitamin B12. Salmon, sardines, and mackerel are important sources of bone-strengthening vitamin D, and a 3-ounce serving of canned sardines with bones contains over 25 percent of a day’s requirement of calcium.
The FDA warns pregnant women—and those who might become pregnant or who are nursing—not to eat shark, swordfish, king mackerel, or tilefish because these may contain mercury, which can damage the brain and nervous system of the fetus. The FDA also advises pregnant women to eat no more than 12 ounces of fish a week and to vary the types of fish they eat.
For a full listing of nutrients, see the National Nutrient Database:
A note on fish oil: Fishoil capsules have become increasingly popular, but they may not have the same benefits as fish since fish is rich in other nutrients. The capsules also come with potential adverse effects, including a reduction in the ability of your blood to clot, which may slightly increase the risk of hemorrhagic stroke. People with bleeding disorders, those taking anticoagulant medications, or those with uncontrolled high blood pressure—a stroke risk—should talk with their doctor before taking fish oil capsules. In addition, the capsules can cause nausea, diarrhea, belching, and a bad taste in the mouth. They are also a concentrated source of calories.
If you have rheumatoid arthritis or psoriasis, fish oil capsules might be worth a try. But be sure to consult your doctor first. Anyone else who wants the benefits of omega-3s should ignore the capsules and eat fish, and ideally, at least two servings a week.
Also, be aware that, as with other dietary supplements sold in the United States, the quality and purity of fish oil capsules is left up to manufacturers—so there is no guarantee that the capsules you buy actually contain omega-3s or even fish oil, or that they are free of contaminants.
Canned versions of fish are a convenient way to add fish to your diet, if you choose carefully, and they can provide the same health benefits as fresh fish, being low in calories and fat and high in protein, B vitamins, and omega-3 fatty acids.
If possible, choose canned fish packed in water, not oil. This applies primarily to tuna, because salmon is so fatty it doesn’t need a fatty packing liquid. Sardines come in both oil- and water-packed versions.
The vegetable oil that is commonly used in canned tuna doubles the calories in the fish and adds up to 10 times more fat. Only 15 percent of the calories in water-packed tuna come from fat, compared to over 60 percent in the oil-packed version. Draining the oil removes about a third of the calories and half the fat, but can also remove the valuable omega-3 fatty acids. One study found that while draining water-packed tuna removed only about 3 percent of the omega-3s, draining oil-packed tuna removed 15 to 25 percent of these valuable nutrients.
Added salt is another nutritional concern with canned fish. Processors usually add four to 10 times the amount of sodium naturally found in fresh fish. Fortunately, “low-salt” and “no-salt-added” varieties are available. “Low-salt” tuna usually has about 50 percent less sodium, and tuna marked “no-salt-added” contains 90 percent less.
Some canned fish have an added health benefit that might not be obvious. The canning process softens the bones of salmon and sardines. If the bones are eaten, these fish can supply significant amounts of calcium—200 to 325 milligrams per 3 ounces.
How to Choose the Best Fish
Overall quality of fish can be judged by sight, smell, and touch—so you'll need to rely on your senses when shopping. Here what to look (and sniff, and feel) for.
Pickled and smoked fish
Since fish is one of the most perishable of all foods, it’s not surprising that techniques for preserving it were developed before the advent of refrigeration. Pickling and smoking are two time-honored methods. Not only do they help preserve the fish, they also alter and enhance its texture and flavor: Pickled herring and smoked salmon are delicacies quite different from either fish in its fresh state.
Oily fish such as salmon, sturgeon, sablefish, and butterfish are favorites for smoking, though trout and whitefish are American smoked favorites. Finnan haddie is a famous Scottish smoked haddock specialty. Herring is sometimes smoked but more commonly pickled. You can choose from:
- Dutch maatjes herring: lightly sugar-cured
- German Bismarck herring: pickled in vinegar with onions
- English kippers and bloaters: salted, cold-smoked herring
- Jewish-style herring in sour cream sauce
In addition to cold- and hot-smoked salmon, Scandinavians prepare gravlax, salmon cured with salt, sugar, and herbs. Lox is salmon cured in brine, while the salmon that is sold as “Nova Scotia” or “Nova” is cold-smoked. British kippered salmon is brined and then hot- or cold-smoked.
Various types of smoked and pickled fish are sold by the pound at the deli counters of many grocery stores, in fish markets, and in gourmet shops. Less-expensive packaged versions are found in the dairy case of many supermarkets.
When sold in bulk, these products will not have nutritional labels, so be aware that they can be very high in sodium. Three ounces of smoked Chinook salmon has 667 milligrams of sodium, for example. The same amount of pickled herring as 740 milligrams of sodium. Since smoked and pickled fish are made from fatty fish, they are relatively high in fat—only 4 grams of fat for the salmon, but 15 grams for the herring. Delectable smoked sablefish is especially high in fat, with nearly 17 grams of fat in a 3-ounce, 219-calorie serving.
Most people eat caviar, if at all, in small amounts and rarely. As an occasional treat, caviar is not bad; it has fewer calories and more nutrients than the same amount of potato chips.
Whether it’s the expensive “real” kind, made from sturgeon roe, or the cheaper roes of salmon, lumpfish, and whitefish, caviar is high in protein: 4 grams per tablespoon. A tablespoon also contains 133 percent of the RDA for vitamin B12, 24 percent for iron, along with vitamin A, vitamin E, and some magnesium. As for calories, there are 40 per tablespoon, or fewer than 80 per ounce. There are no nutritional differences between one type of caviar and another, but there are differences in taste, texture, color, and price.
A tablespoon of any fish roe contains 94 milligrams of cholesterol, almost a third of the recommended maximum daily allowance. However, caviar has a moderate fat content, about 2 grams per tablespoon. Like other fish, caviar supplies some omega-3s: about 1.1 grams, which is comparable to some of the better sources, such as mackerel.
Fresh sturgeon caviar labeled malossol (Russian for “lightly salted”) contains approximately 4 percent salt as a preservative, which works out to about 240 to 300 milligrams of sodium per tablespoon. The sodium content of economy-class caviars—which may be made from “injured” eggs—can go as high as 700 milligrams per tablespoon.
Should you be wary of scavenger fish? No. It’s not really true that scavenger fish or bottom feeders—catfish and flounder as well as shrimp, crab, and lobster—feed mainly off waste. They eat whatever swims or floats by them. And even when dead organic matter is consumed by these bottom-feeding fish, they digest it and use it to form proteins, fats, and carbohydrates. There’s not reason they would be more contaminated than other fish.
How to store fish
It’s best to use fish within a day of buying it, although it can be kept an extra day or two if it is of very high quality and was very fresh when purchased. Whole or drawn fish will keep longer than steaks or fillets.
Place it, still in the wrapper from the market, in a glass or enamel pan in the coldest part of the refrigerator. Fill a plastic bag with crushed ice and place it on top of the fish. Check the fish daily and pour off any liquid that may have accumulated in the bottom of the pan. Replace the ice.
Although pickling and smoking do preserve fish to some extent, they do not eliminate the need for proper storage. Unless canned or vacuum-packed, these products should be stored in the refrigerator, where they will keep for about a week.
How to freeze fish
If you want to freeze fish yourself, you’ll need a freezer that stays at 0°. Fish for freezing should be perfectly fresh and of high quality. Thawed fish is sometimes sold as fresh, so be sure to ask the dealer if you suspect this, because fish that has been frozen should not be refrozen. The faster the fish freezes, the better, so freeze whole fish only if they weigh less than 2 pounds and cut larger fish into fillets or steaks. Freeze whole fish and fillets individually.
Rinse and dry the fish and wrap it tightly in heavy-duty freezer paper or plastic wrap. Overwrap the package with foil or a freezer bag, then label and date the package and freeze it quickly. Packaged fresh fish should be rinsed and rewrapped. Freeze fish that you’ve purchased frozen (and not thawed) in its original wrapping. Frozen lean fish keeps longer than frozen fatty fish. Use frozen fatty fish within six weeks, frozen lean fish will keep for up to three months.
Smoked salmon can be frozen if carefully wrapped, but its texture may change slightly. Also, unless the fish is hot-smoked for a long period of time, or actually cooked, the process of curing, salting, or pickling will not necessarily kill dangerous organisms that may be present in the fish. Freezing at -4° for at least three days will destroy parasites, but this is not appropriate for all types of preserved fish.
11 Recipes for Fish
Don't be intimidated by cooking fish: They can be as easy to prepare as chicken breasts. Here are 11 easy, healthy recipes to get you started.
Published September 17, 2015