Fugu

Takifugu is a genus of pufferfish, often better known with the Japanese name Fugu (Japanese: 河豚 or 鰒). There are 25 species belonging to the genus Takifugu, which can be found worldwide from about 45° latitude north to 45° latitude south, mostly in salt water, but sometimes also in fresh water or brackish water. Their diet consists mostly of algae, mollusks, invertebrates and sometimes crustaceans. The fish defend themselves by inflating their bodies to several times normal size and by poisoning their predators. These defenses allow the fish to explore actively without much fear of being attacked.

The fish is highly toxic, but despite this — or perhaps because of it — it is considered a delicacy in Japan. The most prestigious edible species is the torafugu or Tiger Blowfish (T. rubripes). The fish contains lethal amounts of the poison tetrodotoxin in the internal organs, especially the liver and the ovaries, but also in the skin and the testicles. Therefore, only specially licensed chefs can prepare and sell fugu to the public, and the consumption of the liver and ovaries is forbidden. But because small amounts of the poison give a special desired sensation on the tongue, these parts are considered the most delicious by some gourmets. Every year a number of people die because they mis-estimate the amount of poison in the consumed fish parts.

The poison paralyzes the muscles while the victim stays fully conscious, and eventually dies from asphyxiation. There is currently no antidote, and the standard medical approach is to try to support the respiratory and circulatory system until the effect of the poison wears off. The fish is also featured prominently in Japanese art and culture.

The fish

There are 25 species belonging to the genus Takifugu (formerly known as Fugu, with the exception of one remaining Fugu species). Takifugu can be found worldwide from about 45° latitude north to 45° latitude south, mostly in salt water near coral reefs or the shore, but some species also live in fresh water or brackish water. Their diet consists mostly of algae, mollusks, invertebrates and sometimes crustaceans. All fishes in the tetradon family have strong teeth that may grow too long if the fish cannot consume abrasive food. Fugu can bite if provoked. Not all species are studied in detail, but the most researched takifugu is takifugu rubripes, due to the commercial consumption and breeding of the fish. Takifugu Rubripes, for example, breeds from March to May and lays eggs attached to rocks at a depth of around 20m. Fugu can also change color over time, and they get a darker or lighter color. This helps them to camouflage. A very dark color may be a sign for stress or illness.

The pear-shaped Takifugu is, like all pufferfish, not a very good swimmer and uses mainly the pectoral fins for propulsion. Subsequently they are rarely found in open water, but stay rather close to the ground. Nevertheless, the fish is very curious and active, and in some cases even aggressive against other fugu or other fish. In case of danger, the fish inflates itself by filling its extremely elastic stomach with water (or air when outside of the water) until the fish is almost spherical (hence the name blowfish or pufferfish). For a long time it was unknown how exactly a pufferfish inflates, but recently Dr. Peter Wainwright has analyzed the series of muscle actions, how a puffer fills its mouth with water, and then seals its mouth using a special valve at the bottom of the mouth. This valve flaps upward and covers the entire mouth of the fish. Next, a branchiostegal ray (a modified gill arch) pushes the water down the esophagus into the stomach. The extremely elastic stomach then expands. Depending on the species the fugu can achieve an almost perfect spherical shape.

The fish's main defense, however, is the neurotoxin contained in its internal organs, mainly the ovaries and the liver, to a lesser extent in the intestines and the skin, and only minute amounts in the muscles and blood. This makes the fugu a lethal meal for most predators, including the occasional human.

The toxin is called tetrodotoxin, or more precisely anhydrotetrodotoxin 4-epitetrodotoxin and is about 1200 times deadlier than cyanide. This poison can also be found in other animals such as the Blue-Ringed Octopus, Cone Snails, or even some newts. The pufferfish does not create the poison itself; rather it is generated by the bacteria Pseudomonas within the fish. The fish obtains the bacteria by eating food containing these bacteria. Pufferfish that are born and grown in captivity do not produce tetrodotoxin until they receive some of the poison-producing bacteria, often by eating tissues from a toxin-producing fish. Also, some fish are more poisonous than others. Each fish has enough poison to kill 30 adults.

Apparently due to some unknown selection pressure, intronic and extragenic sequences have been drastically reduced within this family. As a result, they have the smallest-known genomes yet found amongst the vertebrate animals, while containing a genetic repertoire very similar to other fishes and thus comparable to vertebrates generally. Since these genomes are relatively compact it is relatively fast and inexpensive to compile their complete sequences, as has been done for two species (Takifugu rubripes and Tetraodon nigroviridis).

Consumption

Fugu has been consumed in Japan for a long time, although its historic origins is unclear. Bones of fugu have been found in several shell mounds called kaizuka that date back more than 2000 years. The Tokugawa shogunate (1603-1868) prohibited the consumption of fugu in Edo and its area of influence, yet it became common again as the power of the shogunate weakened. In Western regions of Japan, where the influence of the Government was weaker and fugu was easier to obtain, various cooking methods were developed to safely eat these fish. During the Meiji Era (1867-1912) fugu was again banned in many areas of Japan. Fugu is also the only delicacy officially forbidden to the Emperor of Japan, for his own safety.

A rakugo, or comic short story, tells about three men that prepared a fugu stew, but were not sure about how safe it was. To test the stew, they gave some to a beggar. When they checked on the beggar later, he was still healthy, so they ate the stew. Afterwards they met the beggar again who told them that he was happy that they still looked healthy, so now he knew the stew was safe and he could eat it. The three men had been had by the wise beggar.

The most prestigious edible species is the torafugu or Tiger Blowfish (T. rubripes), which is also the most poisonous. Other species are also eaten, as for example T. pardalis, T. vermicularis, and T. porphyreus. The table at the end of the article shows which species contain body parts that can be consumed according to the Japanese Ministry of Health and Welfare. Other genera that can be consumed according to them include the puffers Lagocephalus and Sphoeroides, and the related porcupinefish of the genus Diodon.

The high demand of fugu has led to overfishing. Strict fishing regulations are now in place to protect fugu from being decimated. Most fugu nowadays is harvested in the spring during the spawning season, and then farmed in floating cages in the Pacific Ocean.

Fugu prices rise in the fall and peak in winter, which is the best time to eat fugu, as they fatten to survive the cold. The fugu is shipped to the restaurant alive and stored in the restaurant in a large tank, usually prominently displayed. As fugu are aggressive and have sharp teeth, in captivity the mouths of fugu are often sewn shut to avoid the fish injuring each other. Prepared fugu is also often available in grocery stores which must display official documents which license them to distribute fresh fugu.

Since 1958, only specially licensed chefs can prepare and sell fugu to the public. The fugu apprentice needs a two- or three-year apprenticeship before being allowed to take an official test. The test consists of a written test, a fish identification test, and a practical test of preparing fugu and then eating it. Only 30 percent of the applicants pass the test. This, of course, does not mean that 70 percent die from poisoning; rather, they made a small mistake in the long and complicated procedure of preparing the dish. Due to this rigorous examination process, it is generally considered safe to eat the sliced fugu sold in restaurants or markets.

Furthermore, most fugu sold nowadays comes from fish with only a small amount of toxin. Selling or serving the most toxic liver is illegal in Japan, but this "forbidden fruit" is still sometimes eaten by amateur cooks, often with fatal results. After several homeless people died from eating fugu organs that had been discarded into an insecure trashcan, restaurants in Japan are required to store the poisonous inner organs in specially locked barrels that are later burned as hazardous waste.

A dish of fugu can cost easily ¥5000 (ca. US$50) but it can be found for as little as ¥2000 yen (ca. US$20), and a full course fugu meal can cost between ¥10,000 and ¥20,000 (ca. US$100 to US$200) or more. Due to the expense of fugu, the fish is sliced very carefully to obtain the largest possible amount of meat without the poison. A special knife called fugu hiki is traditionally used to slice fugu and it is usually stored carefully in a separate location from other knives.

While fugu connoisseurs love the taste and the texture of the fugu, many people actually find it rather bland and tasteless. Some professional chefs prepare the fish so that there is a minute amount of poison in the meat, giving a prickling feeling and numbness on the tongue and the lips. The most popular dish is fugu sashimi, also called Fugu sashi or tessa, sliced so thin that the pattern of the plate can be seen through the meat. These plates are often beautifully decorated so that removal of slices is a pleasure as well. The fins of the fish are also fried and served in hot sake, a dish called Fugu Hire-zake.

Vegetables and fugu can also be simmered as Fugu-chiri, also called techiri, in which case the very light taste of the fish is hard to detect among the taste of the vegetables and the dip. Fugu can also be eaten deep fried as Fugu Kara-age. The more poisonous testicles of the fugu can also be eaten; they contain a milky liquid and taste slightly salty. This is also considered to be an aphrodisiac. If the spikes in the skin are pulled out, the skin can also be eaten as part of a salad called yubiki.

In several remote locations, people have devised a complex pickling process allowing them to eat the poisonous parts of the fugu. While the exact methods are kept secret, they involve long and heavy saturations in sake and salt for over three years.

Fugu poisoning

Tetrodotoxin is a very potent neurotoxin and shuts down electrical signaling in nerves by binding to the pores of sodium channel proteins in nerve cell membranes. The tetrodotoxin is very stable and not affected by the heat of cooking. It does not cross the blood-brain barrier, leaving the victim fully conscious while paralyzing the remainder of the body. In animal studies with mice, 8 μg tetrodotoxin per kg body weight killed 50% of the mice. The pufferfish itself has immunity to the poison due to a mutation in the protein sequence of the sodium channel pump on the cell membranes.

If an ingested dose of the fugu's poison is lethal, as more and more muscles are paralyzed, symptoms may include dizziness, exhaustion, headache, nausea or difficulty breathing. For 50 to 80 percent of the victims, death follows within four to 24 hours. The victim remains fully conscious throughout most of the ordeal, but cannot speak or move due to paralysis, and soon also cannot breathe and subsequently asphyxiates. If the victim survives the first 24 hours, he or she usually recovers completely.

There is no known antidote, and treatment consists of emptying the stomach, feeding the victim activated charcoal to bind the toxin and taking standard life-support measures to keep the victim alive until the effect of the poison has worn off. Japanese toxicologists in several medical research centers are currently working on developing an antidote to tetrodotoxin.

As mentioned above, commercially available fugu in supermarkets or restaurants is very safe and, while not unheard of, poisoning from these products is very rare. Most deaths from fugu occur when untrained people catch and prepare the fish, accidentally poisoning themselves. In some cases they even eat the highly poisonous liver on purpose as a delicacy. As not all fishes are equally poisonous, this may not always lead to death, but sometimes give only the desired numbness on the lips and tongue while eating and shortly thereafter. However, in many cases this numbness of the lips is only the first step of a lethal fugu poisoning.

Some sources claim that about 100 people die each year from fugu poisoning, while others sources say only 10 to 20 per year, and still others state only 1 person dies each year from fugu. This reported variation may be the result of different sequences of years being studied, as for example in 1958, the first year the preparation of fugu required a special license in Japan, 176 people died of fugu poisoning. According to the Fugu Research Institute, 50 percent of the victims were poisoned by eating the liver, 43 percent from eating the ovaries and 7 percent from eating the skin. One of the most famous victims was the famous Kabuki actor and "living national treasure" Mitsugoro Bando VIII, who died after eating four servings of fugu liver in 1975.

There are some reports of completely paralyzed but fully conscious victims that were believed to be dead, and woke up a few days later or just before being cremated. In some parts of Japan a fugu victim is put next to his coffin for three days to verify the death. If the body does not decompose, it is not yet dead.

The pufferfish is also reported to be one of the main ingredients used in voodoo to turn people into zombies. According to Wade Davis, an American botanist, the pufferfish is the key ingredient in the first step of creating a zombie, where the tetrodotoxin creates a 'death-like' state. In the second step, hallucinogens are used to hold the person in a will-less zombie state. There was considerable scepticism to Davis's claims; he was widely accused of fraud, and there has been no final statement as to the veracity of his findings.

Scientists at Nagasaki University have reportedly (http://www.abc.net.au/news/newsitems/s1119036.htm) succeeded in breeding a non-toxic variety of torafugu by restricting the fish's diet. With over 4800 fish raised and found to be non-toxic, they are fairly certain that the fish's diet and digestive process are what actually produce the toxins that make it deadly. The non-toxic version is said to taste the same, but be completely safe for consumption.

Social aspects

The popularity of fugu in Japan is an interesting phenomenon. Fugu is a very expensive fish, has some potentially lethal side effects, and is by most people considered to have a very weak taste (although many Japanese gourmets would disagree). The combination of these factors would normally give humans a low preference for its consumption. However, it seems one of the attractions of the low-flavored fish is the risk of potential death, regardless of how low that actual likelihood stands in a commercial restaurant. It can be assumed that the fish would be much less popular if it were not so poisonous.

In the Kansai region the slang name teppo (鉄砲) for fugu, meaning rifle or gun, is a play on words on the verb ataru (当たる), which can mean either to be poisoned or to be shot. In Yamaguchi Prefecture, the pronunciation fuku is common instead of fugu. The former means good fortune whereas the latter is a homonym for disabled.

The Japanese poet Yosa Buson (1716–1783) expressed some of this feeling in a famous haiku:

I cannot see her tonight.

I have to give her up

So I will eat fugu.

Perhaps the most well-known fugu story in America was when the fictional character Homer Simpson of the TV show The Simpsons ate fugu served by an amateur chef. Due to the chef's lack of fugu-preparation knowledge, Homer was given 24 hours to live (before his "heart would explode"), during which he vowed to do all the things he always meant to do but never got around to. However, most of the time was spent either asleep, with his senile father, or in jail. He did survive the 24 hours in the end, to the joy of his family and friends.

An episode of Columbo also involved fugu poisoning, this time, a murder. The perpetrator injected fugu poison through the cork into a bottle of wine. The CSI NY episode "Grand Master" included a novel fugu poisoning murder.

Lanterns can be made from the bodies of preserved fugu. These are occasionally seen outside of fugu restaurants, as children's toys, as folk art or as souvenirs for tourists. Fugu skin may also be made into everyday objects like wallets or waterproof boxes.

There is a fugu museum in Osaka.

Availability

Most Japanese cities have one or more fugu restaurants. They may be clustered together as past regulations had placed limits on where they may open the store and also the location of restaurants made it easier to have fugu delivered fresh. A famous restaurant specializing in fugu is Takefuku, a restaurant in the Ginza district in Tokyo.

Few restaurants in the United States carry "fugu." When served in the United States, it typically does not contain any tetrodotoxin. Thus, though the meat is taken from the same fish, it does not produce any of the sensations for which it is famous.

Takifugu species table

^* Fish that have edible body parts according to the Japanese Ministry of Health and Welfare

See also

• Pufferfish
• Culture of Japan
• Cuisine of Japan
• Seafood

References

• (unknown) (May 17 1996) Tetrodotoxin poisoning Associated With Eating Pufferfish Transported From Japan (PDF file) (http://www.aegis.com/files/mmwr/1996/MM4519.PDF), Morbidity and Mortality Weekly Report, Center for Disease Control
• Theodore Benzer (August 5, 2004)Toxicity, Tetrodotoxin (http://www.emedicine.com/emerg/topic576.htm), EMedicine
• Sueyoshi´, Sueyoshi's pages on fishes (http://www.coara.or.jp/~sueyoshi/data03/fugu00.html). Retrieved Sep 11, 2004
• Fugu Genomics Group at the HGMP-RC (March 2004), The Fugu Genomics Project (http://fugu.hgmp.mrc.ac.uk/). Retrieved Sep 11, 2004
• Greg Elgar, Melody S. Clark, Stephen Meek, Sarah Smith, Sarah Warner, Yvonne J.K. Edwards, Nassima Bouchireb, Amanda Cottage, Giles S.H. Yeo, Yagnesh Umrania, Gary Williams, and Sydney Brenner (1999) Generation and Analysis of 25 Mb of Genomic DNA from the Pufferfish Fugu rubripes by Sequence Scanning (http://fugu.hgmp.mrc.ac.uk/Publications/Elgar_1999/), Genome Research (10), 960-971
• Chunkypuffy. Puffer Catalog (http://chunkypuff.net/puffercatalog.php). Retrieved Sep 11, 2004
• (March 16 2003)Puffer Fish Lair (http://home.earthlink.net/%7Esnebluemoon/index.htm). Retrieved Sep 11, 2004

External links

• Personal Account of surviving a fugu poisoning (http://www.kyoshi.or.jp/inv-haiku/routine.htm)
• Extensive List of all Genus and Species for the family Tetraodontidae (http://f15.aaacafe.ne.jp/~ichthy/hugu/hugu2ka.html)
• Ensembl Fugu Genome Server (http://www.ensembl.org/Fugu_rubripes/)nl:Fugu (gerecht)

ja:トラフグ pl:Fugu ru:Фугу