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I've been to many sushi places and last night I went to a place that I've been to before (not that long ago either). When the sushi came, we noticed that it had wasabi spread on the rice, under the fish.

When we complained we were rudely told that the chef had been doing sushi for 30 years and wasabi is used to kill parasites in the fish.

This is believable since I know in some countries, red peppers are used in foods all the time for the same reason.

However, my understanding of sushi is that the chef is a craftsman who not only picks great fish, but also knows how to find and remove parasites.

My question is, is this normal? Is it proper for the Sushi chef to add wasabi to the sushi to help prevent parasites? If so, how come I've only encountered this practice once out of the many sushi places I've frequented?

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Wasabi is placed under fish ontop of rice to hold the fish in place. Parasites are killed when the fish is flash frozen on the boat it was caught on. –  D3vtr0n Nov 8 '12 at 20:55
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This is perfectly normal, however, I find the common claim that "it is to prevent parasites" a bit dubious (I would think that it would have to be uniformly applied to the entire fish to have any measurable effect). The wasabi is really there to add flavor. In really high-end sushi restaurants in Japan, for example, it is relatively uncommon for the guest to be served a mound of grated wasabi. Instead, the chef applies the perfect amount of wasabi to each piece of sushi. Some chefs will not even serve soy sauce, instead individually brushing on the sauce on each piece. If wasabi is served separately from the fish, it is generally also considered bad form to mix it with the soy sauce (as is commonly done in the US).

Edit: To answer your question about why you've never seen this practice before, here are some possible explanations:

  1. It takes more time/skill/effort to do it properly.
  2. Many sushi restaurants in the US do not have properly trained sushi chefs. In fact, in most areas of the country with little or no Japanese population, don't be surprised if your sushi chef is a Salvadorian who learned from the Oaxacan who learned from the Korean owner of the restaurant. Not that there's anything wrong with that; one of my favorite sushi places is run by an Indonesian. Just keep in mind that the people making you your sushi may have never experienced the "real thing" themselves.
  3. "Real," fresh wasabi is very rare and expensive. Most of the stuff that is used in the US is basically horseradish paste plus food coloring. Restaurants that can both procure and afford to use the real stuff will want to use it sparingly; they wouldn't want to waste it by putting a mound of it on each plate. Therefore, they might be more inclined to use the "proper" technique.

Edit 2: Here is a video in which you can see famous chef Naomichi Yasuda using wasabi in the sushi. It all happens very quickly, but you can clearly see him dip into the bin of wasabi, rub it on the underside of the fish, and then apply the fish to the rice. Here is another video in which Anthony Bourdain explains the "rules" of high-end sushi eating, while dining at the super-famous and super-expensive Sukiyabashi Jiro (the proprietor of which is actually designated as a "living treasure" by the Japanese government). That second video shows the chef brushing on the soy sauce, and the general lack of both soy and wasabi on the plates.

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Thanks. I've only seen korean chefs (which I always thought was weird) but whatever. What you say makes sense. I've only been to one high end resturaunt, but still they didn't serve wasabi on the fish. So...even though I use chop sticks I still look american because I mix soy sauce and wasabi?? Oh well. –  DustinDavis Aug 2 '11 at 20:25
Ah I understand it, one isn't supposed to eat sushi with chopsticks either. It's like eating a taco with knife and fork. –  SevenSidedDie Aug 2 '11 at 22:48
+1 for comment 2. This is a global problem. Lack of real training and therefore people making bad examples of classic foods –  TFD Aug 2 '11 at 23:13
@SevenSidedDie: well, there's worst... you could eat sushi with knife and fork!!! :D –  nico Aug 3 '11 at 7:00
When I lived in Japan, it was quite common to mix wasabi with soy sauce when it was served separately.　It was also normal to eat sushi with chopsticks. Apparently both of these practices are not truly "correct," but a quick search online shows many Japanese having the same doubts about proper eating sushi etiquette, so don't imagine you are causing a major faux pas as many Japanese themselves seem to be unsure of these points. –  user1570 Aug 3 '11 at 7:43
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Looking at several sources the general way to deal with most parasites is by freezing.

Here is some general information:


More details are here:


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The chef's claim is false: Usually, the only side where wasabi is applied is under the fish, so it doesn't slide off the rice.

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Japanese are good at making up things to confuse you, LOL. Wasabi is placed under fish ontop of rice to hold it in place. –  D3vtr0n Nov 8 '12 at 20:45
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The "parasites" claim is quite dubious, and probably mostly folklore, but there has been some published evidence that wasabi slows growth of certain bacteria, including e coli.

http://sciencelinks.jp/j-east/article/200210/000020021002A0124150.php has an abstract of one such study. I've heard the same claim from a book written in the late 80s, so I'm sure it's a widespread belief, but I don't know how long ago the research started. I'm fairly certain that the use of wasabi predates the belief and the research, however.

Most of the commercial wasabi contains a high percentage of mustard, which is the source of most people's sensation that wasabi is "spicy". Coincidentally, mustard is also associated with antibacterial properties. Having eaten a couple of decently-sized wasabi rhizomes in one sitting with fresh soba, I'd say "pungency" is the primary quality of fresh wasabi, and it's a different sensation than mustard. It has a very "clean" taste, which may reinforce people's impressions that it kills bad things.

As ESultanik pointed out, adding wasabi during preparation of the fish is done for flavor, but it has one other side benefit, though this may also be part folklore: The fish is more likely to stay attached to the rice with a dab of wasabi than without. I suspect if you noticed it it was probably sloppily applied, but if you haven't noticed it before, it's quite possible it was just used in sensible moderation.

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+1 That's a good point. The part that I am skeptical about, though, is whether the small amount of wasabi is actually enough to have any sort of measurable effect. –  ESultanik Aug 4 '11 at 15:52
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