What is Ciguatera fish poisoning?

a photo of Star snapper

Ciguatera fish poisoning is a type of food poisoning caused by consuming certain fish that live in tropical and subtropical coral reef areas such as Moray eel, Grouper, Star snapper, Japanese scavenger and Parrot fish.

It is caused by toxins such as ciguatoxin, but it mainly generates from dinophyceae that are stuck to algae. The process of ciguatera occurring involves the food chain. Even if a fish itself doesn’t originally contain toxins, an herbivorous fish may eat algae that turns it toxic. That fish may be eaten by a carnivorous fish, which then accumulates high concentrations of ciguatera in its body. When a human consumes the carnivorous fish it can cause food poisoning in the human. There are as many as 300 species of fish that contain ciguatoxin. The ciguatoxin, which causes the food poisoning, cannot be killed by boiling or grilling, so it can’t be prevented through food preparation.

Symptoms of this food poisoning mainly consist of sensory nerve abnormalities, muscle soreness, itchiness and abdominal pain, but it is rarely fatal. However, it takes quite a long time to recover from compared to other toxins and the average recovery time is said to be two to three weeks. It is vital to diagnose ciguatera fish poisoning as soon as possible. Most symptoms develop within one or two hours and up to to 24 hours after consumption and one unique symptom is dysthermesthesia. This is a form of dysesthesia in which touching cold things feels like its burning. It occurs one to two days after the poisoning and is a known characteristic of ciguatera fish poisoning. Another characteristic symptom of ciguaterafish fish poisoning is joint pain within 24 hours after consuming the fish. In any case, it is important to be seen by a specialist as soon as possible.

Incidentally, the name ciguatera came from Spanish immigrants to Cuba as a name for food poisoning caused by the cigua shellfish in that region. Later it was also used to describe fish poisoning, which causes similar symptoms.


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Revision date: May 9, 2022

The answer to the question, “Can I eat sushi leftovers the next day?”

a photo of Takeaway sushi

Nigiri sushi is generally made with raw seafood. It can be said that the seafood starts to go bad as soon as it is put on warm rice. Of course, at the stage of preparation, there are procedures being taken to reduce the causative micro-organisms of food poisoning. Out of all food that is commonly eaten raw, sushi is considered to have the least micro-organisms that cause food poisoning.

For example, Vibrio parahaemolyticus, a typically known bacteria that causes food poisoning, attaches to seafood, and if the conditions, such as temperature, are just right, it proliferates at double the speed of other food poisoning bacteria. When you are eating at a sushi restaurant, bacteria growth is being suppressed. However, if you take sushi home to eat it, depending on conditions bacteria could proliferate.

This is why as a basic rule, you cannot take sushi home from a sushi restaurant.

So then, what is the difference between sushi sold at the grocery store and prepared at sushi restaurants?

There are obvious differences between sushi made by sushi chefs and take-out sushi, as explained below.

Take-out sushi is lined up at the store, selected by the customer, then eaten at home, which takes time. Therefore, a higher amount of salt seasoning is used compared to Nigiri sushi restaurants, in order to delay the degradation in quality. Sushi made by sushi chefs at restaurants has a salt content of about 1% in the sushi rice, while that of take-out sushi has about a 2% content.

Next, with a pH of around 4.5%, it is difficult for bacteria such as Salmonella, Staphylococcus aureus, E. coli bacterium bacteria and Vibrio parahaemolyticus to proliferate, and there are experimental results that show they die out. In an experiment that measured the pH of sushi rice in take-out sushi, it was usually measured at 6%. Nigiri sushi made at a restaurant is often around 6.2%, so this acidity is put to good use in the sushi rice and could be delaying degradation.

Furthermore, although it may not be a pleasant topic of discussion, preventing spoiling and deterioration in food caused by micro-organism is done by adding preservatives to improve the shelf life. For example, classic preservatives such as benzoic acid, Sorbic acid and PH adjusters are used all over the world. There is an obligation to list these on the product label when used.

Now let’s get into the main topic.

This all being said, sometimes when you buy take-out, there are leftovers. There is no question that it is better to promptly discard them. But you may think that you can just eat it the next day, right?

You can. And it will taste the same as when you bought it.

First of all, there is something important to remember; not all toppings are equal in take-out. Unfortunately, things that require freshness like shellfish, squid, mackerel and sardines, cannot be saved. These must be consumed on the day they are bought.

Next, let’s go over how to eat your day-after sushi so that it still tastes good.

The toppings this method works for are tuna, salmon, white fish and steamed shrimp. However, the only white fish it works for are benthic fish such as flounder. As long as the meat is still transparent the next day, it’s safe. For Hamachi, which always has more than 20% body fat, which oxidizes, so avoid keeping it to the next day. Raw shrimp is out too. Steamed shrimp becomes more delicious when quickly put into sushi vinegar for storage.

The method is simple!

First, remove the Nigiri sushi topping from the rice. Next, wash that topping with running water for a few seconds and then dry well with a paper towel. Make sure you are quick in all of these steps. Finally, wrap in plastic wrap and store in the refrigerator.

Next, use a wet paper towel to wrap the sushi rice. Wrap this set in plastic and put it in the vegetable drawer if possible. If you don’t have a vegetable drawer than the normal refrigerator compartment is fine.

The next day, when you are ready to eat, heat the sushi rice in the microwave at 1000W for 10 seconds. The point is just to warm it up a little. Next, just take the topping from the refrigerator and place it on the rice. You can add some wasabi if necessary.

Incidentally, if you use this method for take-out sushi, even when consuming it on the same day, it will taste even better than just eating it right away.

The practice of sushi chefs is to put somewhat cold sushi toppings (16~19℃) or room-temperature toppings (20~23℃) on top of sushi rice that is the same temperature of the human body (37℃). We are trying to imitate this method. If you are consuming on the same day, any topping can be removed from the rice and prepared like this.

But please do not wait any longer than the next day to eat any leftovers.

Do not bend this rule. Let me warn you that the symptoms of food poisoning from shellfish and silver-backed fish are horrible. It should also go without saying that if the sushi rice has already dried out, there is no bringing it back, even with this method. Once you’ve reached that point, you just have to throw it away. Naturally, you cannot eat smelly sushi toppings.


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Revision date: April 1, 2022

What is Yake or Yake-maguro?

An illustration of Longline fishingTuna fishing methods include Purse seine fishing, Fixed-net fishing, Drift-net fishing and Longline fishing, among others. Ocean fishing for tuna in the South Pacific Ocean, Indian Ocean and Atlantic Ocean, is often done by longline fishing. A main line can exceed 150 km in length and have over 3,000 hooks hanging from it. A main line is let out for 6 to 7 hours, and it takes 3 to 4 hours from running the line in the sea, to catching tuna. After that it takes another 10 to 15 hours to reel it up, so the tuna that was caught early may have already died during this time. There are times when sea water may feel warm to the touch, even in the dead of winter. The problem here is, that the body of the tuna that died early, will be warmer if the sea water is warmer. The body temperature will also be unusually high if a tuna caught by a hook ends up struggles for a long time and dying before being reeled in. The same is true for Kuromaguro caught in game fishing.

When this tuna is cut into pieces, the meat is whitish, as if grilled in a fire, so it is called “Yake (焼け)” or “Yake-maguro (焼け鮪)” as “Yake” means “burnt” in this case. The meat can also be a grayish-brown. In the industry it’s known as “White tuna” due to its color. It loses its characteristic red color, the texture of the meat when eating it is flakey and it doesn’t taste good.

Even if the fish body is cooled with ice water after catching, once the meat has been “burnt”, it won’t turn back to red. This renders even the premium Pacific bluefin tuna and southern bluefin tuna worthless, with zero commercial value as food. However, the fishermen don’t just toss the dead fish back into the sea without a second thought. This is mostly processed into pet food. Also, since it can’t be determined externally whether the meat is “burnt” or not, no one can tell until the fish has been cut open. It runs a big risk to the broker and can be a cause of its fishing port brand losing credibility.

It is currently believed that burnt tuna occurs from high temperature and low pH in the muscles of the fish after death, and that there is a complicated, indirect causal relationship between the conditions such as the environmental temperature, fishing method, handling of the catch, length of processing time, type of fish and size of fish. However, the mechanism that causes this phenomenon is not clearly understood.


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Revision date: March 1, 2022

What is used as a substitute for the expensive Mongou ika?

an image of mongou ikaNo people in the world love squid more than the Japanese. Squid ranks third in import volume behind shrimp and tuna. Squid is brought to Japan from the oceans all over the world. There are between 400 and 500 species of wild squid on Earth. Some, like the pygmy cuttlefish, are tinier than 3 millimeters while the giant squid is over 10 meters.

There are about 100 species of squid that live in the waters surrounding Japan. Surume ika (Japanese common squid) makes up the highest volume of domestic-caught squid. It is used as a Yari ika or Surume ika topping in eastern Japan, but Surume ika isn’t used very often in western Japan. At sushi restaurants, squid like Sumi ika (Golden cuttlefish), Aori ika (Bigfin reef squid), Kensaki ika (Swordtip squid) and Mongou ika (Ocellated cuttlefish) go for high prices, but they are all caught in smaller quantities and therefore only available to high-end sushi restaurants that can procure them fresh.

There are some conveyor belt sushi restaurants that list Mongou ika (モンゴウイカ又はカミナリイカ) on the menu, but actually serve European common cuttlefish (ヨーロッパコウイカ). It is produced in the waters off the coast of West Africa. Even some sushi restaurants do this. This is actually still too pricey for conveyor belt sushi though. What is generally used at conveyor belt sushi is Flying squid (アカイカ), which goes for only 1/10 the price of the European common cuttlefish and reaches 60 cm in length. Jumbo flying squid (アメリカオオアカイカ) is also often used. The Jumbo flying squid is more than twice as long as the Flying squid and exceeds 1 meter in length. The Jumbo flying squid is mainly imported from places on the other side of the world such as Chile and Mexico. The thickness of the meat is similar to Mongou ika. However, a big drawback is that the Jumbo flying squid lacks the sweetness peculiar to squid. Therefore, it is soaked in water that has been artificially sweetened. This alters the dried out sensation to a plump, moist sensation, making the customer believe it is Mongou ika.

The squid must have a certain thickness in order to masquerade as Mongou ika. Rhomboid squid (ソデイカ), which has a torso length of 80 cm is also disguised as Mongou ika. Rhomboid squid is found in the warm waters of the world and is even caught in relatively high volume in Japan. Large squid have a low price cost, so it’s good for the shops to make a profit. Furthermore, the sweetness is brought out more when frozen first than by serving it fresh. That means it can be used as Mongou ika without any need for the artificial sweeteners used in Flying squid and Jumbo flying squid.

The fact is that there are many substitute products for Mongou ika. But even so, it doesn’t change the fact that using ingredients disguised as others is an unacceptable practice.


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Revision date: March 1, 2022

The general rule is to only eat oysters in months that contain the letter “R”.

In other words, avoid them from May to August.

an image of oysterIt’s won’t hurt you to eat Magaki (Japanese oyster), which has its spawning season in the summer, but in the months with no R in the name, the glycogen concentration is low, so you can’t get the full-bodied texture that you get in winter. In addition, almost all amino acids such as glutamic acid, glycine, alanine, arginine, which are important components for delicious flavor, are known to accumulate from winter through spring, and conversely, they decrease in the summer, which is the spawning season. You cannot expect the same deliciousness from oysters in summer as you can from months that contain the letter R.

Furthermore, the oyster takes in large amounts of seawater and filters out the plankton for its food. Therefore, in warm seasons it fills up on large volumes of the toxic plankton that proliferates in the sea. Eating toxic plankton can make the oyster toxic and toxified oysters can cause food poisoning when consumed by humans. In addition, in the warmer months, the oyster loses its freshness faster after being harvested, increasing the likelihood of getting a bad one and risk food poisoning. Therefore, it’s best to not go out of your way to eat oysters in summer.

On the other hand, one certain oyster is actually in season in summer.

Iawagaki (Rock oyster) is known as the summer oyster. This type is close to the Magaki, and it lives attached to reefs at depths of 2 to 20 m, deeper than the intertidal zone and facing the open sea. A large Iwagaki has a shell length of 10 cm, a shell height of 20 cm or more and weighs more than 1 kg. However, the edible part is small compared to the size of the shell. It is an oviparous hermaphrodite. Growth is slow at a rate of around 5 cm in one year, around 7 cm in two years. It takes three to four years to reach 10 cm or more and grow big enough to harvest.

The glycogen volume in Iwagaki is high from March to July, peaking around May, and it then decreases from September to October. The main production areas are the Sea of Japan on the coasts of Akita, Yamagata, Niigata, and Tottori. Many of the Iwagaki in circulation are harvested from the wild, unlike Magaki, which is almost all farmed.


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Revision date: February 1, 2022

A lesson on how the price of Nigiri sushi is determined

In order to prosper, a business wants to sell products at as high a price as possible. So how does a chef determine the price of nigiri sushi?

Naturally, the cost price is what it costs the restaurant for the ingredients while the price on the menu is the selling price. The ratio of these two prices is called the cost rate. In the case of a sushi restaurant, the ideal cost rate is 35% or less. A restaurant operating with only Omakase will have a cost rate of 40% with a focus on the quality of the toppings.

For sushi restaurants, handling of this ratio and the yield are very important. Yield refers to the part of the purchased fish and shellfish that can actually be used. For example, when purchasing a whole fish there are bones, skin, eyes, tail and internal organs that cannot be served as sushi or sashimi. No matter how good a chef is when preparing fish, the bones and skin will remain. In other words, the yield rate is the percentage of parts that can be used as sushi or sashimi. Typical fish yield rates are as follows:

Wild Maguro (Tuna): 65~75%

Buri (Japanese amberjack): 50%

Hirame (Bastard halibut): 40%

Tai (Red seabream): 35%

Akagai (Ark shell): 25%

Mirugai (Keen’s gaper): 20%

The weight of just the topping for a single piece of nigiri sushi is 12 to 18 grams, depending on the ingredients and the policy of the restaurant. The market price for rice is said to be about US$5 per kilogram, and assuming a weight of 15 grams per Nigiri, the rice for a piece of sushi is generally said to cost about US$0.05, including vinegar and salt. Even if you count the shari (sushi rice), soy sauce, wasabi, nori, etc., it’s fair to consider the cost to be about US$0.10.

Now, let’s figure out the price of Hirame, for which 3 kilograms were bought at $60 per kilogram. Assume that the weight of one topping is 15 grams.

The yield rate of Hirame is 40%, so the chef can make 1,200 grams of sushi toppings from 3,000 grams of Hirame. (formula: 3000 g × 0.4 = 1200 g). Since the weight of one topping is 15 grams, 80 pieces of sushi can be made from 3,000 grams of Hirame (1200 g ÷ 15 g = 80 pieces).

Next, we calculate the cost of one topping. Hirame is US$60 per kilogram, so US$180 (US$60×3 = US$180) for 3 kilogram. Since this volume can yield 80 pieces, the cost of one topping is US$2.25 (US$180÷ 80 pieces = US$2.25).

Add the shari price of US$0.10 to this: US$2.25+0.1=US$2.35. In other words, the cost of one Hirame nigiri sushi is US$2.35.

If the ideal cost ratio of 35% is applied here we get 2.35÷0.35 (35%) = US$6.71. For a restaurant serving mainly Omakase, 2.35÷0.4 = US$5.88.

In summary, one piece of Hirame sushi is sold between $5.88 and $6.71.

It may feel surprisingly cheap, but if you perform these calculations with Kuromaguro or Uni, it will be $60 to $90 per piece, and then you’ll feel that it is too expensive. Therefore, the total margin is secured by setting the cost rate for Kuromaguro and Uni to 80-90%, while the cost rate for Saba and Ika is set to 10-20%.

See Sushiuniversity


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Revision date: January 6, 2022

Is the combination of Chablis wine and Japanese oysters match made in heaven?

White wine is generally thought to go well with fresh seafood.

For example, every Frenchman knows that Chablis wine and Belon oysters go together like peanut butter and jelly. The soil of Chablis is made of the stratum that dates back to the Kimmeridgian age and a unique characteristic is that the soil is rich in fossils of small oysters and shellfish. That is why oysters and Chablis wine are said to be the perfect pairing. However, surely there are Japanese people who sense the fishy odor when having Chablis wine and Japanese oysters (Magaki) together. Therefore, some people say that sake is definitely preferred over wine.

The reason for this is that the types of oysters in France and Japan differ.

Famous for its Belon brand name, the oyster native to Europe has a flat, rounded shell. It belongs to the genus Ostrea. To be honest, Belon oysters aren’t sweet and don’t have a distinguished flavor compared to Japanese oysters, and the salty fragrance of the sea is dulled, so it can seem less flavorful.

Meanwhile, the Japanese oyster is elongated and shaped like a raindrop. It is characterized by a smell like it swallowed the whole ocean. This is the main species farmed in Japan. It belongs to the genus Crassostrea. The taste is as if the umami components of the sea have all been concentrated together in one little shell.

Going back to pairing Chablis wine with oysters, it’s common sense in the world of flavors that items with basically similar components pair well together.

The issue lies in how wine is made. Chablis wine contains lactic acid because it is made through forced mal-lactic fermentation. Because it contains this lactic acid, it is partially fighting against the Belon oyster, which has a high glycogen content. In addition, lactic acid is called “warm organic acid”, and it has the property of becoming delicious at warm temperatures. Oysters are eaten cold, so they aren’t good for taking advantage of “warm organic acids”.

Therefore, it can be said that rather than Chablis wine, it goes well with cold organic acid white wine that is delicious when cooled to 7 or 8 degrees, for example, German Franken wine.

So then, what should be done when pairing oysters with Chablis wine?!

If you insist on pairing oysters with Chablis wine, go all out and add squeezed lemon so the citric acid will work to mask the lactic acid and succinic acid, in turn making the wine taste good even when cold. Citric acid is a “cold organic acid” that becomes delicious when cooled, and oysters rich in glycogen go well with “cold organic acid”. Cold acid-based white wine is abundant in the refreshing “cold organic acids” known as malic acid and tartaric acid. Oysters lack this cold organic acid (malic acid and tartaric acid), so adding the citric acid of lemon creates an exquisite harmony.

However, in France there was a time when a disease spread that caused the death of the Belon oyster, nearly rendering it extinct. Therefore, since the Japanese oyster has been transplanted so many times, it is said that nowadays, at least 90% are Japanese oysters hybrids of Japanese oysters.

That means the question remains among Japanese as to whether the combination of Chablis wine and oysters really is a match made in heaven or not. Personally, we’ve never heard of oysters served without lemon, so the fishy smell really isn’t an issue at all in the end.


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Revision date: January 6, 2022

What is used as a substitute for Madako (Octopus)?

Among the many sushi toppings, Pacific bluefin tuna, and actually the Madai (Red sea bream) as well, are toppings that are difficult for an amateur to tell whether it is farmed or wild. However, there is no need to worry about that when it comes to Tako (Octopus). There are no octopus farms to be found in the world, so it is a 100% wild topping.

In Japan, domestic production isn’t enough to satisfy the appetite of Japanese who like Tako, so the majority relies on imports. Imports from Africa account for 80% and the remainder is imported from China, Southeast Asia, Mexico, Spain and other places in the world.

Most of the African imports are produced by nations on the northwestern coast, with the highest number coming from Mauritania. Until 2003 the highest volume came from Morocco for many years. However, due to continued mass catches to sell to Japan, Tako numbers dropped drastically, leading to the Moroccan government panicking and outlawing fishing. For some reason, Japanese people have grown to love Tako and now consume nearly half of the Tako caught throughout the world.

There are over 200 types of Tako in the world with approximately 60 types inhabiting the seas near Japan. Among these, the Japanese mainly only eat Madako, Mizudako and Iidako. Even among these, Madako makes up at least 80% of consumption.

Most of the Tako found at conveyor belt sushi is African Madako (Madako from Africa). African produced Tako is boiled on-site before being imported frozen. The cost is 20 cents or less per topping.

Amateurs can’t tell the difference between domestic Tako or African imports. However, there is one aspect that even an amateur can use to distinguish between the two. There is one condition for this to work, and that is that at least one of the suckers is in-tact. The suckers are scraped off for most toppings, but in cases where they are sliced by the restaurant, there are often suckers remaining. If the sucker is pure white, it is almost definitely from Africa. Meanwhile, domestic Tako suckers maintain a faint red color in the suckers, even when boiled. The reason the suckers turn white seems to be an effect of the food preservatives added during processing, but this has not been confirmed.

There happens to be a substitute for Madako as well.

One of these is the Iwadako from Vietnam, which grows as large as the height of an adult human. It is imported in frozen slices that can be used as raw Tako as soon as it thaws. The cost of this topping is 20 cents or less per piece. This ends up disguised as Hokkaido Tako.

There are also domestic substitutes. Yanagidako (Chestnut octopus) is mainly caught in the Pacific Ocean, from Chiba prefecture northward. The flavor is lighter than Madako, but it is also softer than Madako, so some people actually consider it to be better than Madako. If it is boiled and made into sushi, an amateur can’t distinguish between it and Madako. The legs are thin so they just need to be cut at an extreme angle in order to make the topping appear bigger. The cost of this topping is 15 cents or less per piece. It is also used as Mizudako because it is watery when eaten raw.

As you can see, there are also many substitute toppings for Madako.


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Revision date: December 21, 2021

What is Toro Katsuo (Torogatsuo)?

Toro is an absolute at sushi restaurants and it’s only natural to aspire to such a position. That’s why there are so many sushi dish names that start with “Toro”. The most laissez-faire of these is Toro salmon. In this case the definition of Toro is ignored in an attempt to promote sales. Just as bad is Toro katsuo (pronounced “Toro-gatsuo” in Japanese).

Katsuo is born in the warm southern seas. When it reaches about two years old it migrates north in pursuit of Iwashi and other small fish. There are two routes taken by the Katsuo that come to the seas around Japan. One of the routes rides the Kuroshio Current (a warm current) from around the Philippines, passing by Taiwan and the Ryukyus Islands, arriving in southern Kyushu. From there the Katsuo rarely heads toward the Sea of Japan and instead the majority moves northward on the Pacific Ocean side. The Katsuo migration schedule may shift depending on the temperature of the seawater and how the schools of Iwashi and Aji (which the Katsuo feeds on) are migrating that year. The first group appears around Ishigaki Island about January, then in the seas off the shores of Kyushu and Shikoku between February and March. It then moves to the seas off of the Izu and Boso peninsulas between April and June. It reaches the open seas off the southern coast of Sanriku and Hokkaido between July and September.

Another route follows the Ogasawara ocean current from below the equator in the seas off the shore of Papua New Guinea and the seas around Micronesia to the Ogasawara Islands, along the Seven Islands of Izu and approaching the open seas off the Boso Peninsula. The route then goes northward to join with the routes mentioned above.

It’s the Modori-gatsuo that begins reverse migration toward the south at the beginning of autumn when the water temperatures start to drop. Katsuo has a strong appetite before returning south in preparation for the long trip. Unlike the light-flavored Hatsu-gatsuo, the Modori-gatsuo has plenty of fat and its body fattens up quite a bit. The main fishing locations for Modori-gatsuo are in the northern Pacific, such as the waters off the shore of Sanriku. This is the season when it is truly worthy of the name Toro katsuo when served raw, and nothing else should be called by the same name.


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Revision date: December 1, 2021

What is Warisu?

Warisu refers to the vinegar when doing Sujime.

The fish is first washed in water, then soaked in vinegar. When working with blue-backed fish, the smell of the fish’s fat is removed from the surface with vinegar that has been used once before (and thus has a low acidity). This is called Suarai. When preparing fish with Sujime, cooled Warisu is used, made either with a 10 to 3 ratio of vinegar to ice, or the same ratio of vinegar to cold water. Vinegar with a high acidity that hasn’t been cut with water only soaks the surface of the fish (denaturing it) and the vinegar does not penetrate to the inside. In addition, if the temperature of vinegar is high, such as during summer, the skin and body of the fish soften. That’s why the vinegar is diluted (acidity is between ph 3.3 and ph 3.7) and used as chilled Warisu. After the Sujime of the topping is finished, it is important to place it in the refrigerator and allow the meat to mature slowly. For fish with strong fat, that fat oxidizes faster than the meat can mature, so it must be done very carefully.


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Revision date: November 23, 2021

What is Meki? Substitute for Kuruma ebi?

Japan leads the world in shrimp consumption by far. Most of the shrimp is imported, but it is a little known fact that shrimp is called “Meki” among importers and sushi restaurants in Japan. It is said to be a remnant from a time when much of the imported shrimp came from Mexico (pronounced “Mekishiko” in Japanese).

Shrimp can be caught within 45 degrees north or south of the equator. The caught shrimp is quick-frozen on site and then sent to Japan. Mexico was early in advanced refrigeration technology so when it became impossible to catch shrimp in the seas around Japan in the 1970s, a large volume of shrimp was already being imported from Mexico. It was around that time that importers shortened the phrase “Shrimp imported from Mexico” to “Meki”.

After that the major source of shrimp imports switched to Taiwan, which started shrimp aquaculture, and it is now also imported from Thailand, Indonesia and China. The name “Meki” stuck in the industry, despite the fact that shrimp is now mainly imported from other places in Asia.

Imported shrimp is categorized by body color tones, either brown, pink or white. The color is combined with the place of origin or country name and that is what each type of fish is called at the distribution stage. For example, they may be called Mexico brown or Guiana pink.

Well-known brown-toned shrimp include Ushi ebi (Black tiger shrimp) and Mexico brown (Yellowleg shrimp). Pink-toned types include Guiana pink (Pink spotted shrimp) and Nigeria pink ebi (Southern pink shrimp). White-toned shrimp include Taisho ebi (Fleshly prawn),  Banana ebi (Banana Prawn) , Eedeavour ebi (Eedeavour prawn) and Vannamei ebi (Whiteleg shrimp). There are many sushi restaurants that use pink and brown-toned sushi that turn into a nice red color when boiled. While the meat of white-toned shrimp is soft, it turns a whitish color when boiled and doesn’t look very appetizing. However, due to the splendid, large tail, it is perfect for tempura or fried prawns.

Next, We will touch on the characteristics of shrimp that is typically imported to Japan. All these types are actually related to the Kuruma prawn, which is representative of premium shrimp and a familiar ingredient of sushi. In other words, these imports are alternatives to make up for the shrimp consumption in Japan that can’t be covered by the Kuruma prawn. Normally the head is removed, it is frozen, packed in large lots, and then embarks on the distribution channel in Japan.

Guiana pink (Redspotted shrimp, Spotted pink shrimp /Farfantepenaeus brasiliensis)

For more information, go here.

Taisho ebi (Fleshly prawn /Fenneropenaeus chinensis)

It is found from the Indian Ocean to the Pacific Ocean, the Malay Archipelago and Australia.  The species is of considerable commercial importance in the Yellow Sea, East China Sea and Korean Bight, where it is trawled. It is sold in Korea, China, Japan and Hong Kong. This is a large shrimp that reaches up to 25 cm in body length. The appearance is similar to the Kuruma ebi, but without any special pattern. The edge of the abdomen is a dark brown color. There are 28 known species related to the Kuruma ebi. In the Toyosu market, those with a striped pattern are Kuruma ebi, and those without are Taisho ebi. In Japanese it’s been dubbed “Korai ebi” is due to the fact that it is often caught in the waters off the west coast of the Korean peninsula. The soft meat has a sweetness that makes this shrimp delicious. The number of wild Taisho ebi has decreased drastically in recent years. The coloring is lighter than Kuruma prawn and Black tiger shrimp, but darker than other white-toned shrimp. This type has a long history compared to other imported frozen shrimp and such high volumes were imported from China that it was called Chinese Taisho. It accounted for the majority of the market share until farmed Black tiger shrimp started to appear on the market.

Banana ebi (Banana Prawn /Penaeus merguiensis)

Weighs between 18 to 30 g per shrimp. This shrimp comes from Australia and is colored like a banana. The meat is soft and has a sweetness. Sometimes it is also sold as Taisho ebi. The body is thinner and slenderer than the Black tiger shrimp.

Mexico brown (Yellowleg shrimp, Brown shrimp /Farfantepenaeus californiensis)

For more information, go here.

Vannamei ebi (Whiteleg shrimp, Pacific white shrimp/ Litopenaeus vannamei)

For more information, go here.

Ushi ebi (Black tiger shrimp, Giant tiger prawn/ Penaeus monodon)

For more information, go here.

Australia tiger(Brown tiger prawn /Penaeus esculentus)

This is a reddish-brown colored shrimp with a striped pattern from Australia. It is often imported with the head intact. The meat has a sweetness and the soft coloring is also nice. It is used as an alternat to Kuruma prawn. Most are caught in the wild, especially in Australia’s Gulf of Carpentaria.

Nigeria pink ebi (Southern pink shrimp, Candied shrimp/Farfantepenaeus notialis)

It occurs at depths from 3 to 700 m, common at depths from 10 to 75 m, inhabits bottom mud or sandy mud, and sandy patches among rocks in marine environment. Juveniles are found in estuarine environment. Also inhabits lagoons. It is often used for sushi because of the soft meat, good flavor and nice coloring. This is one of the highest grades of imported shrimp.

Mexico ebi (Northern brown shrimp, Brown shrimp /Farfantepenaeus aztecus)

Maximum standard length: 22 cm. It lives in bottom mud or peat, often with sand, clay or broken shells. Adults inhabit in marine environment. Juveniles inhabit in estuarine and marine environment. There are 13 types of brown-toned Kuruma prawn in the world and the names get confusing.

King ebi (Eastern king prawn /Penaeus plebejus)

Adults are found in marine environment while juveniles are found in estuarine environments. It is found over sandy bottoms at depths of 2-350 m or deeper.

Finally, the shrimp introduced in this section is consumed not only in Japan, but all over the world. Judging by the images on social media, takeout sushi and the frozen shrimp sold at Costco are made from one of the types of shrimp described here. If you’re going to learn about sushi, it’s important to learn the types of shrimp used in sushi.


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Revision date: January 4, 2022

What is Sekisaba?

Sekisaba (関サバ) and Sekiaji (関アジ) are ‘designer’ fish known for their high prices.

Of them, Sekisaba is a premium fish that can go for as high as US $50 per fish. So, what kind of fish is Sekisaba and what’s the difference between it and normal Saba (Mackerel)?

Sekisaba is a Saba caught in the Hoyo Strait with a fishing pole by a union member of the Saganoseki branch of the Oita National Federation of Fisheries Cooperative (JF Oita). In other words, Sekisaba is not a type of Saba, but a premium fish created by differentiating the fishing method.

Sekisaba started to become known all over Japan between the late 1980s and early 1990s. Until then, Sekisaba was only known as a commonplace fish that was caught incidentally with Aji and went for US $2 per fish.

However, the Saganoseki branch of JF Oita applied for the first trademark ever in the industry and then grew the brand through methods such as tagging each individual fish by hand. This resulted in recognition of its taste as “Saba that can be enjoyed even as sashimi” (while Saba is generally a fish that loses its freshness easily and not eaten raw), catapulting it to a national constituency  After that, the thorough quality management and branding paid off and the price jumped to 10 times that of normal Saba.

The first difference between Sekisaba and normal Saba is that Sekisaba is caught carefully, one at a time. The use of ground bait is also banned so that the Sekisaba won’t eat anything but the natural diet (avoiding odor). Each fisher is only allowed to use fishing lures they make from fish skin or ragworms. Fish caught in this way are let out into a live holding tank on the ship and brought to the fishing port alive. After arriving at the port, the tank on the ship is checked, the fish size is looked at from the water surface and the approximate weight is measured. This method is called “Tsurugai”. This is because when the fish is placed on a scale, it struggles violently and can injure itself. The fish are allowed to calm down in the tank for a day at the fishing port. At the time of shipping, Ikejime is performed, in which a knife is put into gill parts, the spinal cord is cut, and then it is submerged into saltwater and the blood is let out. After that a processing method called Shinkeijime is performed in which a wire is inserted into the spinal cord to put the fish in a state of asphyxiation. Therefore, there is little damage to the fish, maintaining the freshness.

The Hoyo Strait where Sekisaba is caught is rich in plankton, which the Sekisaba feeds on, and the flow of the tide is fast. The reason Sekisaba meat firms well and is fatty year-round is thanks to the good environment of the sea it is raised in.

If you come across a Sekisaba that so much work has been put into, try it as sashimi, not Nigiri sushi. This is because Saba, which has a peculiarity to it, is unpopular among some people. However, Sekisaba doesn’t have this off-taste and doesn’t taste like Mackerel, so even people who don’t care for fish should be able to find it tasty.


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Revision date: October 25, 2021

Hirame isn’t thought of as a high-end fish in the US!?

Hirame is a high-quality fish that goes for at least US $50 per kilogram. It can even exceed US $80 per kilogram, depending on the timing and the fish’s body.

Hirame is a typical white meat fish when winter is approaching and a great sushi topping to start off a meal. Also, the taste is so delicate that the original flavor can be cancelled out just by adding too much soy sauce. How the chef expresses this delicate taste is a tribute to his skill and something that foodies look forward to.

In the US, Hirame is often written as “halibut” on the menu of sushi restaurants. Technically the English name of Hirame is Bastard halibut. Hailbut (referring to Pacific halibut) is called “Ohyo” in Japanese. In Japan, the engawa of massive Ohyo is often used as a substitute for Hirame engawa at conveyor belt sushi, but the two are not confused for each other. There is no mistake that Hirame is related to halibut, but they are completely different species. Incidentally, the price of Ohyo is US $3 to $20 per kilogram. It is incomparably cheaper than Hirame.

Also, depending on the restaurant it may be represented in a variety of other ways such as fluke, flatfish and flounder. These terms refer to relatives of Hirame (鮃) or Karei (鰈), but do not indicate any certain species of fish. In other words, there is generally no distinction between Hirame and Karei in the US and to go even further, all white fish are thought to be the same species.

The delicious taste of fish is dependent on the distribution of fat and the amount of inosinic acid. Therefore, fish taste better in the seasons when they have fattened up. On the other hand, people have a hard time distinguishing between types of fish when comparing the tastes of the parts with less fat. The free amino acids in fish meat differ only slightly between different types of fish. In other words, the flavor of all fish is mostly the same. It is only the amount of fat and the amount of the umami component, inosinic acid, that differ between fish, so apparently even sushi chefs cannot distinguish between fish just by eating the back part, which has a low fat content.

This is part of the reason why in the US all white fish is all lumped into the same category and to top it off, the common consensus there is that white fish has no flavor.

At sushi restaurants in Japan, generally there are at least two types of white fish on offer. It is practically guaranteed that Hirame will be in stock in winter. The light flavor unique to this white meat that spreads with each bite maximizes the aroma and sweetness of the vinegared rice. Recently, white fish with high levels of fat such as Kinmedai and Nodoguro, have become standard, high-quality white fish.

The difference between how even these sorts of white fish are handled in the US and Japan is astonishing. That said, flavorless Hirame is not consumed as sashimi or sushi even in Japan. It is served in dishes with strong flavors, like carpaccio. It’s possible that delicious Hirame is just not available in the US.


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Revision date: October 7, 2021

What is Ishigakigai sushi?

Ishigakigai is a shellfish found from Kashimanada northward, Hokkaido, from the Kuril Islands to the Aleutian Islands and even on the west coast of North America. It lives off of plankton in the shallow sandy mud bottoms of the sea at depths of about 50 meters.

Aquaculture in Hirota Bay, Iwate Prefecture, has been successful and it started to appear at the Tsukiji Fish Market starting in about 2008, distributed as Ishigakigai. According to brokers, someone in the business at Tsukiji Fish Market misheard “Ishikage” as “Ishigaki” and the name stuck in the market. While Torigai meat looks black, Ishigakigai looks whiter, so it is also called “Shirotorigai”. The official name is “Ezoishikagegai”.

It starts to become common at the market when the Japanese rainy season ends, at the beginning of summer every year, which is around the end of the Torigai season. It then disappears from the market at the end of summer. A number of sushi restaurants start using it as a substitute for Torigai all at the same time, so Ishigakigai nigiri sushi suddenly started appearing on menus. Frankly, it is somewhat conservative as a nigiri topping but is known for the crunchy texture when biting into it. It also has strong sweetness and umami, which goes exquisitely with Shari. The sushi chef slaps the meat in his hand directly before serving to stiffen it–a way to increase the crunchy texture characteristic of shellfish. Naturally this texture is evidence of its freshness.

As the season of availability is short and the production sites are limited, Ishigakigai often fetches a high price. Those up for sale at the Toyosu Market go for $2 to $4 each. Wild-caught Ishigakigai is rarely found on the market, but when they are, the price is double that of the farmed version.

A relative of the Torigai, the Ishigakigai is rich in amino acids such as taurine, glycine and arginine. It is also resilient and can live for days, even outside its shell.

Related contents: Ezoishikagegai


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Revision date: October 5, 2021

There are strangely two types of Ama ebi

It goes without saying, that each type of fish has its very own scientific name. However, in places like the Toyosu Fish Market, there are seafoods that end up sharing a name.

The official Japanese name of ama ebi (sweet shrimp) is “Hokkoku Akaebi” (scientific name: Pandaluseous Makarov).

In Japan, ama ebi lives naturally along the Sea of Japan coast and the coasts of Hokkaido, and the ama ebi sold at Toyosu market is caught from Toyama prefecture and northward to Hokkaido and southward. When made into nigiri sushi, it is harmonious with the acidity of the vinegared rice and the thick sweetness is irresistible. It really lives up to its “sweet” name.

However, what dominates the Toyosu Market is frozen shrimp of the same pandalidae family, called “Honhokkoku Akaebi” (scientific name: pandalus borealis kroyer) from Iceland and Greenland.

This is distributed as “Ama ebi” at the market, but strictly speaking it is a different type of shrimp. As far as appearance goes, it is impossible to tell the difference and they say that even the flavor is the same.

The majority of ama ebi used at conveyor belt sushi is produced in Greenland and imported to Japan through China. The reason for this import circumvention is that the processing to turn the shrimp into ready-made sushi toppings is done using inexpensive labor in China. The frozen ama ebi is thawed in China, processed (head, shell, etc., are removed) and then frozen again. Of course, this process diminishes the freshness of the fish. Preservatives are used to help prevent this. For example, pigment fixing agents are used in order to reduce discoloration from fading. Furthermore, acidity regulators and antioxidants are used to prevent changes in the quality and color of the meat. Ama ebi is stored in packs of 50, imported en masse to Japan, and can be used for sushi or sashimi immediately upon thawing.

As this ama ebi caught in the North Atlantic Ocean is considerably cheaper than domestic ama ebi, the reality is that conveyor belt sushi wouldn’t survive in Japan without these imports.


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Revision date: September 1, 2021