What Is "Sushi-Grade," Anyway? A Guide to Eating Raw Fish at Home

Few foods can rival a sliver of raw fish, impeccably fresh and minimally adorned, whether it's perched atop a mound of sushi rice or swimming in a spicy citrus bath. And yet, despite the popularity of incredibly simple dishes like sushi, sashimi, crudo, poke, and tartares on restaurant menus, for many cooks, preparing raw fish at home remains a daunting task.

In part, this stems from uncertainty about the risks of eating raw fish. Many people will gladly place their faith in an anonymous sushi chef at a random restaurant, but nevertheless shy away from the potential dangers of homemade ceviche. Cooks comfortable with chopping up raw beef for tartare may think twice about doing the same for striped bass.

And then there's the issue of availability. Many Americans struggle to find fresh seafood, and even those with access to good fish markets are rarely sure of their ability to gauge the freshness of fish, both whole and filleted. That can drastically reduce their confidence in eating fish at all, let alone raw.

Finally, additional confusion has been borne out of some widespread and misleading terminology. Some fish markets will have a section of their display cordoned off, containing a few pristine-looking pieces of tuna and salmon labeled "sushi-" or "sashimi-grade." A great fish market may advertise sushi- or sashimi-grade hamachi and fluke as well. But, as anyone who has eaten much sushi knows, there are plenty of other fish in the sea. In indicating that these fish are safe to eat raw, the labels also imply—erroneously—that others are not.

I spoke to several experts to help demystify what "sushi-" and "sashimi-grade" mean, and to outline best practices for preparing fish at home for raw consumption.*

*The information in this guide applies to fin fish and flat fish only. Raw shellfish, including crustaceans (like shrimp and lobster) and mollusks (oysters and clams), are subject to their own set of considerations, which unfortunately lie beyond the scope of this article.

The Short Version

If you know what to look for in fresh, whole marine fish (freshwater fish are susceptible to tapeworms and probably best avoided), as well as how to fillet them, then your decision to eat raw fish other than tuna and farmed salmon at home comes down to your individual comfort level with risk. To be 100% sure of avoiding parasites, you'll have to stick to tuna and farmed salmon. But if you are willing to accept a small risk of infection—a risk that's also present in any fish that hasn't been grievously overcooked—then all you have to do is keep your fish cold and your preparation area and tools clean, and you're good to go.

"Sushi-Grade" and "Sashimi-Grade"

Officially, the terms "sashimi-grade" and "sushi-grade" mean precisely nothing. Yuji Haraguchi, owner of the Brooklyn-based Osakana, a fish shop specializing in sashimi, recalls using them for marketing purposes when he worked as a sales representative for wholesale fish distributor True World Foods. Back in 2004, the company was trying to expand its customer base beyond Japanese restaurants, and Haraguchi's mission was to convince other restaurants to serve their customers raw fish besides tuna. "The term 'sushi-grade fish' was very effective in terms of making sales, but at the same time, I had to provide the right product and the right information," he says. Davis Herron, director of the retail and restaurant division at The Lobster Place fish market in Manhattan's Chelsea Market, agrees: "It's a marketing term that has little significance [with respect] to actually being able to consume raw fish."

The appropriation of sushi and sashimi for this purpose makes sense, since many Americans eat raw fish primarily in Japanese restaurants. It's the "grade" portion that is entirely misleading. There is no national governing body that grades fish in the same way that the US Department of Agriculture (USDA) grades beef. Although the Food and Drug Administration (FDA) issues advisory guidelines that sketch out processes for handling a variety of fish meant for raw consumption, those guidelines are not intended to determine the quality of the fish in the way marbling determines the quality of beef—only its relative safety for eating raw. So when you see a piece of fish labeled sushi- or sashimi-grade, that means that the seller has judged it safe to eat raw. The claim is only as trustworthy as the fish market that makes it.

What the FDA Guidelines Mean (and Why Tuna and Farmed Salmon Are So Common)

Regulations regarding fish sold for raw consumption vary from state to state, although every state points to FDA guidelines as the gold standard; the key difference between the states is whether those guidelines are enforced. Haraguchi and Herron note that both the New York City Department of Health (which regulates restaurants in NYC) and the New York State Department of Agriculture and Markets (which regulates fish markets throughout the state) have adopted the FDA guidelines as law. While those recommendations are primarily focused on limiting pathogenic bacterial growth (more on that below), they do include rigorous specifications for killing parasites.

Herron describes those specifications this way: "Any wild fish except tuna species—bigeye, yellowfin, bluefin, bonito/skipjack—those wild fish need to be frozen for specific periods of time at specific temperatures to get rid of parasites." The exact temperatures and times can be found on the FDA website, but suffice it to say that those temperatures, reaching as low as -31°F (-35°C), are well below what a home freezer can reliably produce and maintain, which is why it isn't advisable to try this at home. Sushi restaurants and fish markets use what's called a "super freezer," which is exactly what it sounds like: a freezer that maintains super-cold temperatures. (Osakana's super freezer, for example, maintains a temperature of -60°F/-51°C.)

This FDA table details the species-specific risks of live parasites in fish; the information here is a little misleading, however, and meant to serve more as an agency warning about the perils of mislabeling fish than as a practical guide to which fish must be frozen prior to raw consumption. Exempted from the FDA's freezing requirements are, as Herron mentions, large species of tuna—deemed safe based on the frequency with which they are eaten in raw form and the infrequency of related, documented parasitic infection—as well as aquacultured fish, like salmon, given verification that the feed it's raised on is parasite-free. To meet FDA guidelines, every other type of fish must be frozen to those temperatures, even if the table does not indicate that it carries a parasite risk, because it "may have a parasite hazard that has not been identified if these fish are not customarily consumed raw or undercooked."

It's a paradox: The FDA will not deem a fish free from parasite hazards, and thus safe to eat raw without freezing, unless that fish is eaten raw, without being frozen, frequently enough to present sufficient evidence of its safety. To Luke Davin, the general manager of Osakana, this standard means that "deviating from [the FDA's] 'freeze it all' approach puts the burden of testing and proof on the processor." He says that most, if not all, fish markets lack the resources to exhaustively test the fish they receive for parasite hazards. The easiest solution, then, is simply to freeze everything.

How Dangerous Are Parasites? Depends Who You Ask

Despite the FDA's blanket recommendations for the elimination of parasites, which is the main goal of its freezing guidelines, very few infections from eating raw fish have been documented in American medical literature. In the US, eating raw fish that hasn't been frozen is rare enough that the agency's "Bad Bug Book" uses Japan as a reference point, since the practice is far more prevalent there. But even in Japan, where freezing of fish meant for sashimi is not required, reported infection rates are vanishingly small compared to the total population. (For instance, the Bad Bug Book reports "more than 1,000 cases" of infection by anisakis worms, the most common parasite in marine fish, reported annually in Japan, but keep in mind that's out of a total population of ~127 million in 2015.)

Because some infections are asymptomatic, and many are thought to go unreported, the risk of infection may be greater than statistics suggest. On a less scientific level, worms—particularly parasitic worms—inhabit dark recesses of our collective imagination. The idea that eating a piece of seemingly pristine, delicious fish carries a risk of infestation by alien-like organisms is enough to give anyone—including health authorities equipped with all the relevant, fear-assuaging data—the heebie jeebies.

Both Haraguchi and Herron point out that, in certain cultures, fish has long been served raw despite never having been frozen at all, and neither was bothered by the idea of eating fish under those circumstances (though they stress that the fish they sell for raw consumption has been frozen according to FDA guidelines). Of parasites, Haraguchi says, "It's natural. Parasites are as natural as seeing a ladybug in farmers' market vegetables." When I tell Herron that I myself have purchased fluke at The Lobster Place, butchered it, and eaten it raw at home, he says, "I've done the same thing. I'm fine, you're fine. And everybody was doing that before these regulations came out, and everyone was okay."

But there are caveats: Freshwater fish and some anadromous fish—fish, like salmon, that divide their life cycles between fresh and salt water—are susceptible to broad fish tapeworms, which are widely considered more harmful than other parasitic worms. Few experts recommend eating fish in the cod family—particularly Atlantic cod, but also Pacific cod, haddock, and pollack—since they're highly susceptible to infection by a range of parasites. (According to Haraguchi, there's another reason fish in the cod family are not eaten raw: "There's so much moisture [in the flesh], it doesn't taste good.")

The parasites that infect most marine fish are nematodes, or roundworms, from the genus Anisakis. It's preferable to avoid eating them, of course, but conventional wisdom says that the stray live anisakid in your gut will, at worst, provoke some discomfort—nausea and possible stomach pain, similar in kind to a bout of food poisoning.

Dr. Judy Sakanari, a parasitologist in the Department of Pharmaceutical Chemistry at the University of California, San Francisco, believes that this view downplays the risks of ingesting anisakids. "Infection by these parasites can be very serious and can lead to resection [surgical removal of part of an organ] of the intestine," she warns. Sakanari stresses that understanding the life cycle of the parasite is necessary to a full appreciation of the risks involved.

All parasites seek to reach their end-host organisms. For tapeworms, these are bears and other fish-eating mammals; for anisakids, they're marine mammals, such as whales, seals, and dolphins. If all goes as the parasite gods intend, fish carrying infectious worm larvae will be consumed by an end-host organism. But if those fish are snatched up in a trawler or caught on a line, the ideal parasitic life cycle is interrupted. As soon as the fish's body temperature begins to rise to that of the end-host mammal, the parasite larvae in its gut will attempt to find a way out, leading them to burrow into the fish's flesh. This is one reason why it's always best to keep ungutted fish cold: Any parasite larvae in the fish gut will remain immobile as long as the temperature is sufficiently low.

That impulse to find a more hospitable environment, Sakanari says, is what makes anisakids particularly worrisome for humans. The human body is sufficiently different from that of whales and elephant seals—typical anisakid end hosts—that it forces the worms to wander around inside of it. As they do so, they probe along the intestinal wall, trying to penetrate it and sometimes getting stuck in the process, which can necessitate resection. (Interestingly, because humans are a natural end host for tapeworms, Sakanari says that tapeworm infection, as disgusting as it might sound, would be preferable to larval anisakid infection. The pathologies associated with the adult fish tapeworm infection are by and large less severe, and can be treated with a simple anthelmintic.)

Sakanari notes that preparations like ceviche, in which fish are submerged in an acidic bath, do nothing to kill off anisakids, since they thrive in highly acidic environments. Candling—in which a strong light is shined through thin fish fillets placed on a glass, in order to spot parasites to be removed—is also not foolproof: Sakanari describes an experiment in which she and her colleagues examined a piece of rockfish using this method and determined that it was free of parasites. After cooking, they then flaked the fish fillet and examined it, and found that they had, in fact, missed several worms. Even experts can fail to completely deworm a fillet.

The upshot of all this: The only real way to be sure that you've eliminated any parasites in the flesh is by using temperature. "It's best to properly freeze or cook the fish. That's the bottom line," Sakanari says. Is it worth the risk to eat raw fish that hasn't been properly frozen? "It depends on how much you love the dish," she says. "There are always risks to eating anything raw and improperly prepared or washed, so it is incumbent upon consumers to be aware of the risks and how to prevent the infections."

Temperature Abuse and Bacterial Contamination: The Real Danger

Haraguchi and Herron agree that parasites in raw fish are less of a concern than bacterial contamination. "At the end of the day, we can freeze this product—so we've gotten rid of the worms—but you could temp-abuse it at home, we could temp-abuse it here, there's a million different things that can impact the bacterial count on that fish," Herron says.

By "temp-abuse," or temperature abuse, Herron means that the fish could be kept at unsafe temperatures for a long enough period of time to encourage the growth of pathogenic bacteria. Generally speaking, fish must be kept below 40°F (4°C) to inhibit that growth. Bacterial strains of all kinds are worrisome to health authorities, but some are specific to certain kinds of fish. For example, above 40°F, tuna, mackerel, sardines, and herring are susceptible to the growth of bacteria that produces histidine decarboxylase, an enzyme that produces scombrotoxin (also known as histamine), which can cause symptoms of poisoning in humans. Histamine is not eradicated by cooking or freezing, so it's a particular concern for fish purveyors.

In addition, fish processors and markets must limit the introduction of pathogens, which means that those who work with the fish must work clean—in clean facilities, with clean tools and clean hands—and minimize their contact with the fish flesh. Fish sellers have a vested interest in keeping their product as pristine as possible, to maximize their chances of selling it before it goes bad. But home cooks who want to prepare raw fish at home should take similar precautions: sanitizing their work areas and tools, working with clean hands, touching the fish flesh as little as possible while they prepare it, and doing all they can to keep the fish as cold as possible.**

**Note that pathogenic bacterial growth is a function of temperature and time. If a piece of mackerel rests at room temperature for several hours, it is not irremediably contaminated. The FDA guidelines include a range of acceptable periods of time that fish can be kept at higher-than-refrigerated temperatures, although the general rule is that the colder you keep your fish, the longer it will keep and the safer it will be to eat.

Beyond the Safety Basics

At Osakana, Haraguchi's idea of what it means for a specific fish to be sashimi-grade depends not just on the safety of the fish, but also on its quality. First, Haraguchi does not source any farmed fish. (Farmed fish, he says, tastes more like fat and less like the fish itself, due to the feed it's raised on, so he avoids it.) Instead, he sources wild, local fish, and his suppliers know that he intends to sell that fish as sashimi. This gives Osakana the benefit of securing some very fresh fish that has been handled in such a way as to minimize bruising of the flesh. The trade-off is that Haraguchi and his staff—and their customers—have to be flexible, depending on what's available.

The fish Osakana receives is never allowed to stay whole overnight. Instead, it is scaled, gutted, and de-headed; carefully washed in running water; and filleted. Some fish undergo further treatments in order to make the skin edible—for example, the skin on Spanish mackerel is torched, and boiling water is used to blanch porgy skin in a process known as yubiki—while others are skinned. The fillets are then allowed to air-dry in a refrigerator designed to maintain a controlled temperature and humidity level to reduce the moisture content in the flesh, a process sometimes referred to as "aging." "Taking the moisture out is sanitary, and it makes the fish more flavorful," Haraguchi says, noting that "a lot of people make the mistake of packing fish right after it's filleted, and there's a lot of moisture still left, whether it's from the fish or from the water used to clean the fish." After the fish has sufficiently dried, it's frozen in a super freezer to kill parasites. "Of course, freshness is important," Haraguchi says, "but the most important thing is how it's handled the closer it gets to the table or the customer."

The results speak for themselves. Not only does Osakana offer a range of fish for sashimi that's rarely found at other fish markets—I found porgy, sea trout, tilefish, and Spanish mackerel on a recent visit—but the fish flesh is both visibly and texturally altered: a little darker, a little firmer, and drier in the mouth, with a flavor that's a tad more pronounced. To test this, I ordered from Osakana a whole Spanish mackerel, which the shop gutted, de-headed, and cleaned but otherwise left untouched. (This is a service Osakana provides to any customer, given advance notice.) I filleted the fish myself and sliced it up into sashimi. While it was undoubtedly quite fresh, it paled in comparison to the Spanish mackerel sashimi you can buy, either in blocks or presliced, from the store's display case.

Tips for Preparing Raw Fish at Home

Assess Your Fish Market

Osakana and The Lobster Place are not typical fish markets; there aren't many shops out there that treat their fish better. But if you're unsure of whether to trust the products and claims of a fish market you've happened to wander into, you don't need to speak to the fishmonger (although it never, ever hurts to establish relationships with the people who are selling you food). Instead, you can use The Lobster Place as a kind of visual guide—it is a model for not just fish presentation but safe handling practices as well. Fish fillets are placed on aluminum trays, set in an overabundance of crushed ice with sufficient drainage, and oriented so that their flesh touches other fish flesh as little as possible. Whole fish are buried in ice, with each fish set in a posture similar to the way it swims through the water. (This is done to account for the way the innards settle due to gravity; keeping an upright-swimming fish upright ensures that one side doesn't end up squished, which would detract from the quality of the flesh.) The fish cutting boards behind the counter, where the staff cut whole fish into fillets in full view of customers, are hosed down and sanitized regularly. While looks can be deceiving, the vast displays of fish never smell off or fishy; instead, the air has a clean, marine smell.

Buy Whole, Fresh Marine Fish (but Not Cod)

Haraguchi says that even at a clean, well-maintained, trusted fish market, he'd be wary of buying fish fillets that are not specifically designated for use in raw applications, and that in most cases, it's better to simply buy whole fish from the market and fillet it yourself. Gauging freshness is easier with a whole fish (check for bright red gills, eyes that are bulbous and clear, flesh that's firm and unblemished) than with a fillet (smell and tightness of the muscles are pretty much all you have to go on). If you know what to look for in whole fish, you can shop for fish anywhere, even in markets that are less aesthetically appealing. For raw preparations, buy the freshest marine fish available, avoid fish in the cod family, and avoid freshwater fish, assuming you're not interested in a tapeworm infection (if you are, godspeed). If you wish to completely eliminate the parasite threat at the purchase point, ask if the fish market has a super freezer and whether they'll freeze the fish for you; if they won't, you're better off sticking to tuna and farmed salmon.

Keep Your Fish Cold

Those who catch their own fish or shop at live fish markets should keep a couple things in mind. First, barring immediate evisceration, keeping a fish cold is the best way to minimize the risk of parasites moving from guts to flesh. Second, rigor mortis can affect fish flesh—its texture, its taste, and how it responds to being cut into fillets. (The effects of rigor on fish flesh were studied in depth by the folks at the Cooking Issues blog in their examination of the ikejime butchering technique.) You may want to let your fish rest (refrigerated) before filleting, and you may want the fillets to rest (refrigerated) before consuming.

If you are filleting more than one fish, or if you're inexpert at filleting, as I am, I strongly recommend keeping a container lined with ice packs (as detailed here) on hand, so that you have a cold place to keep your fillets without having to constantly open and close the refrigerator.

If you're filleting fish that won't be cooked right away, be sure to keep the fillets as cold as possible, and keep them covered.***

***Although Haraguchi's point about avoiding excess moisture still stands, home refrigerators run very dry and can desiccate exposed fish flesh.

Scale and Gut the Fish Yourself

If you're buying your fish whole, and you question the sanitary conditions of the market, it's best to scale and gut the fish yourself—for which you'll need a good fish scaler, a pair of fish tweezers, and a boning knife—but you can also ask the fish market to do this for you. (But do the filleting at home, to ensure that the process is as sanitary as possible.) If you gut the fish yourself, be sure to wash out the blood and guts thoroughly with running water.

Ensure Your Work Area, Tools, and Hands Are Clean and Dry

At home, make sure your work area and tools are as clean as possible, and that the counter and cutting board (preferably a reversible one) have been sanitized properly, on both sides, using a bleach solution. (To sanitize a cleaned and rinsed cutting board or kitchen counter, spray on a solution made with one tablespoon of bleach per gallon of water. Let the surfaces air-dry, or allow the solution to sit for at least 30 seconds before wiping the board dry.)

Dry both the fish and the cutting board very thoroughly, using clean kitchen towels or paper towels, and, of course, make sure your hands are clean before you begin skinning and cutting.

After you've skinned your fillets, transfer them to a clean container or plate, and either clean and sanitize your cutting board again or flip it over to the clean side before you proceed with cutting up the fillets. Throughout this process, touch the fish flesh as little as possible, both to minimize the risk of introducing pathogens and to avoid imparting off flavors to the fish.

Look for Worms

As you slice the fish for the final preparation, keep an eye out for parasites. Do this even if your fish has been frozen according to FDA guidelines—freezing kills parasites and prevents them from doing you harm, but it does not remove them—and even if you are using farmed fish. Anisakid larvae range in color from brown to white, are about a centimeter in length, and look very much like watch springs. Broad fish tapeworm larvae will be encased in a cyst, which looks like a diminutive grain of rice embedded in the flesh. Just use your fingers to remove them, or, if you're squirmy, fish tweezers.

If you want to be really thorough about parasite removal, you can hold thin fillets (of fluke, say, or flounder) against a glass plate and shine a strong light through it, which will reveal many, if not all, of whatever parasites may be in the flesh. Similarly, cutting your fish in very thin slices will increase your chances of discovering parasites.

Eat Up! Recipe Ideas

Need ideas for what to do with your raw fish? You could serve it as sashimi, thinly sliced, with a little soy and some wasabi, or, even better, some yuzu kosho. Or serve it as crudo, with some good olive oil and a finishing salt. Or, if you want a more defined recipe, why not try our Peruvian-style fish ceviche or aguachile? The possibilities are really endless.

Here's hoping that some of you find the risks of eating raw fish to be far outweighed by its gustatory charms. For the true believers, the information provided here should give you the confidence to go out and pick up a whole fish of some kind—a beautiful porgy, say—and discover the range of opportunities that fish beyond tuna and salmon offer to the home cook.

Read More

• How to Fillet a Fin Fish
• Seafood Fraud: The Turning Tides of an Industry Epidemic