trans Fatty Blog: Fun with Raw Fish

I've never tried making sushi or sashimi, mainly because it strikes me as a whole separate craft from cooking, and one I know nothing about. But as a person who eats sushi regularly, I was curious: what exactly is sashimi-grade fish?

The World Wide Web is full of sites that advertise sashimi (or sushi)-grade fish, but this is the same Web that brought us the I Love You virus. Vendors may be reputable, but if they aren't, what recourse do you have?

The Government doesn't have the answer. The U.S. Government doesn't even recognize a sushi grade, and since seafood inspection is voluntary; most fish is never inspected anyhow. Yet sushi and sashimi are increasingly common, sold everywhere from fine dining restaurants to takeout lunch joints to the local supermarket, where the guy behind the counter doesn't exactly look like the Iron Chef. So how do you know it's safe?

As far as I can tell, it boils down to two simple rules:

1. Somebody has to claim the product is fresh and wholesome enough to be eaten raw.

2. You have to believe it.

Is it Safe?

Don't get me wrong; I like sushi and eat it regularly. I just like to know the rules of the game before I play.

According to the FDA, seafood products overall are as safe to eat as any animal product, and far safer than chicken. But those calculations are based largely on cooked seafood products. Add raw oysters and other uncooked molluscs to the mix and the risks increase considerably, though seafood still comes in safer than chicken overall. It's unclear where sushi and sashimi items fall on this scale.

For any seafood product, risks can be divided into two categories: either the fish was infected or contaminated with something before it died (environmental risks), or the fish was allowed to spoil or become contaminated after it died due to mishandling.

Fish is one of the last hunted products, meaning that people climb into boats, sail out to sea, and catch it from the wild. (While more and more seafood is farmed, this is still true for many fish products.) This results in specific environmental risks including:

Parasites such as roundworms or flatworms that may be present in fish muscle tissue. This risk is greatest for freshwater fish, or those that spend part of their lives in fresh water (such as salmon).

Natural toxins, including ciguatoxin, saurines, scrombrotoxin, and paralytic shellfish poisoning (PSP) caused by red tide.

Pollutants including polychlorinated biphenyl (PCB) or Mercury.

Since toxins and pollutants tend to concentrate up the food chain, the risk for these contaminants is greatest in large fish at the top of the chain. These fish also tend to live longer, giving poisons more time to accumulate in the liver and other organs.

Spoilage Risks

Fish are more subject to spoilage and mishandling than other animal products, for a number of reasons:

Since fish are cold-blooded, the digestive enzymes naturally present in fish have evolved to be effective at low temperatures, and are therefore less likely to be slowed by refrigeration. These enzymes may also be particularly powerful to digest crustaceans and other creatures swallowed whole. The challenge is to "eat the fish before it eats itself."

Bacteria present in fish are also more likely to multiply under refrigeration, for the same reason.

For fish caught in the wild, the stress of being caught is likely to deplete reserves of stored glycogen in muscle tissue which would otherwise break down to lactic acid, a natural preservative.

In the case of shellfish, the animals are not typically gutted, so the viscera (guts) -- which decompase particularly quickly -- remain.

Finally, fish are higher in unsaturated fats, which go rancid more quickly.

The Good News

In spite of these risks, fish not only tastes good, but is good for you. It's naturally tender and low in connective tissue; it's also low in fat and high in omega 3 fatty acids which are known to reduce levels of "bad" LDH cholesterol. The reason for the tenderness of fish has to do with the watery environment in which it lives; the density of water makes it harder to move and easier to sit still. As a result, much less of a fish's body is devoted to the skeleton and infrastructure that a land animal needs to hold it's body shape; far more is devoted to the fast-contracting, short fibered (and tender) muscles that provide a burst of speed in an emergency.

Handling Fish

When handling fish, there are some things you can do to reduce the risks, but no perfect solution.

Above all, buy from reputable sources. Duh.

To locate parasites, white fish like cod and haddock can be held over a light box (candling).

Freezing at -20°F for 2 days kills parasites and some bacteria.

Marinating in acid (as in seviche) kills some bacteria but not parasites.

Cooking to 140°F kills bacteria and parasites but doesn't destroy toxins.

Whom Do You Trust?

You can trust your senses; if it smells badly then throw it away. You can trust the crowd as the local sushi bar; if they sell to hundreds every week and nobody has keeled over they must be doing something right. You can trust the Japanese, who know fish better than anybody. The finest tuna may be caught off Maine or Newfoundland, purchased on site by Japanese buyers and shipped to Tokoyo for processing, then shipped all the way back to New York to be sold in the city's finest restaurants.

Is sushi worth the risk? Not if you're elderly, very young, sick or otherwise vulnerable, or if you're pregnant. But otherwise, of course it is. As Anthony Bourdain writes, good food always carries an element of risk. The body is not a temple, it's an amusement park.

Comments

Jon,

Really liked the article on raw fish. I buy raw salmon at the local grcery, smell it and eat it raw all the time hoping for the best!

Posted by: ellen | July 16, 2004 at 09:20 AM

I like reading all info on raw fish, like you said your body is not a temple it's an amusement park. bought some bad fish once and had to get off the ride and puke my guts out dont wish food poisoning from fish on anyone. Thought I was dying. That never stopped me from eating fish I used to eat sushi 2 to 3 times a week when living in Toronto, Timmins well not too many Japanese people here. I've been scared to make my own sushi did for the first time last night and I hoped for the best.........had raw tuna it was so good I should have done this long ago been here for 3 years now really missed my sushi. I only been eating it in my dreams here in Timmins. So from now on it's Sushi night at least twice a week.
Sushi Girl in Timmins

Posted by: S.K.Timmins | September 04, 2004 at 11:11 AM

Very informative article. I feel lucky, as the natives in my area have fresh salmon and other seafood readily available. I would like to emphasize your statement that if it smells bad, don't eat it. Most seafood sold at the local grocer smells bad. Always give your seafood the sniff test before purchase. Fish is extremely healthy for us. Anyone who frequents the fast food chains, ought to replace this habit with a relaxing visit to the local sushi bar instead. You will most likely see a dramatic change in many of your bodily functions.

Posted by: Tiffany | June 12, 2006 at 12:48 PM

I loved your post on pros and cons of consuming raw fish. After I started making my own sashimi, it's hard to go back to sushi restaurants. I am currently investigating whether freezing salt water fish is really necessary. The parasites in them are really rare. If you happen to know of any articles on this matter, drop me a line.

Can't wait to read more of your blog.

Cheers,
-Helen

Posted by: Helen Rennie | August 08, 2006 at 08:43 AM

The parasites are relatively rare, but seem to be related to poor handling.
I.E., not cleaning the fish quickly enough, and/or not freezing properly.
Make sure you buy "sushi" grade to ensure best possible care in handling...

One possible pathogen:
http://vm.cfsan.fda.gov/~mow/chap25.html

Posted by: Jim H | August 08, 2007 at 07:52 PM

Nice bog you have here. I pretty much lurk the internet when I'm bored and read all I can about the organic lifestyle, but I really liked you view on things. I'll bookmark the site and subscribe to the feed!

Posted by: Acai Powder | August 26, 2008 at 01:15 AM

Sashimi is my "happy food".
For years I thought indulging had to come at a price by going to a sushi bar, ordering to my heart's content, tiping the sushi Master, in all due courtesy, and limping home, $100 lighter. Turns out I can purchase gorgeous center cut fillets of salmon, yellowfin, and albacore, (luv salmon skin hand rolls), organic soy sauce, and wasabi, from Fresh & Easy or Trader Joe's, (and a 6 or 12 pack of brew), jam home, and feast healthfully (okay, the brew doesn't necessarily count), all the while saving funds, for a more frequent treat to me!
There IS something to be said for presentation, and atmosphere, when a sushi Master is found who appreciates an open pallet, and will delight in tantilizing tastebuds with creativity, and simplicity alike, but when I crave the simple, buttery, calming, sanctuary of fresh Atlantic or Alaska salmon sashimi, with an ice cold lager, why not enjoy at home, where the salmon is hand cut by me, and the brew has no stoppage (not to mention, no drive home to worry about!)??? Otherwise, I totally am willing to pay for a hand roll to die for, made by my favorite sushi Master...taste the luv...

Posted by: Sarah | September 01, 2008 at 03:43 PM