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Fish, explained.

Everything you need to know to make great fish, whether you’ve bought it or caught it yourself, including:

What to look for when buying fish, and how to store it after you buy
How to scale, gut, and fillet fish
How to bake, grill, broil, steam, braise, and fry fish

Fish Basics

Fish have always been a staple of the human diet, especially among coastal populations. As the human population has grown, its impact on fish in the wild has been significant—during the 20th century, stocks of numerous fish in the wild declined alarmingly as a result of various factors, including overfishing, pollution, and the development of industrial fishing techniques. To fill the demand for fish, fish farming (or pisciculture), which is a rapidly expanding industry, has begun to compensate for declining stocks. Much of the fish sold in stores today comes from fish farms as opposed to the open sea.

Types of Fish

Fish comprise more than 20,000 different species. All of these different species vary widely in terms of shape, size, and color. The texture, taste, and nutritional value of each species’ flesh also varies greatly. Even so, all fish can be categorized in a few different ways:

Saltwater vs. freshwater: The vast majority of fish species live in the ocean, but some are found in freshwater (rivers, lakes, streams). Certain so-called anadromous species, such as salmon, leave the sea to spawn in freshwater, while catadromous species, such as eels, leave freshwater to spawn in the sea. For more information on freshwater or saltwater fish, see the Quamut guides to Freshwater Fish and Saltwater Fish.
Flatfish vs. oval fish: In contrast to most fish, which have an oval body with a vertical orientation, flatfish, such as flounder, are horizontal. These fish are the same shape as other fish at birth, but at a certain point in their development they tilt to one side, gradually becoming flatter and less oval. Eventually the eye on the underside shifts to the exposed side, and the fish swim on one side for the rest of their lives. The underside, or “blind” side, of flatfish loses pigment and becomes white, while the exposed side changes color, helping the fish blend in with the sand on the ocean floor. For more information on flatfish, see the Quamut guide to Flatfish.
Fatty vs. leaner: Some fish have more fat than others. Prominent examples of “fatty” fish include salmon and trout, while most white fish are lean. As explained in Nutritional Information: Fish, a “fatty” fish is not less healthful than a leaner fish.

Contrast Between Fish and Other Meats

Fish and meat have several significant differences. They affect the nutritional value of fish and the ways in which you can cook fish:

More muscle: Fish has a higher proportion of muscle than meat does because the connective tissue that links the muscles together in fish comprises only 3% of the flesh (as compared to 13% of meat). For this reason, fish can be cooked more quickly than meat and is also more tender than meat. The muscle fibers in fish are also shorter than those in meat, which makes the flesh more tender.
Easier to digest: Fish flesh can be cooked very quickly and contains little fat. This makes fish easy to digest, which explains why you may sometimes feel hungry after eating fish, especially leaner varieties.
Less pigment: Fish flesh contains far fewer blood vessels than meat and little or no pigment, which is why most fish flesh (with some notable exceptions) is white in color.
“Good” fats: The fat in fish consists mainly of omega-3 polyunsaturated fatty acids, which are found in few other foods (meat contains mainly saturated fatty acids). See Nutritional Information: Fish for more on omega-3.
Since polyunsaturated fat oxidizes faster than saturated fat, fish is more perishable than meat. The fattier the fish, the faster it spoils.
Since the juices in fish are less dense than those in meat, the liquid that is released as fish cooks can be used to make relatively clear, delicately flavored sauces.

Fish and the Spawning Season

The flesh of fish that are spawning is generally considered less appetizing because its texture isn’t quite as good. The spawning season varies from one species to another but generally lasts from January to June in the Northern Hemisphere.

Acknowledgments & Disclaimer