Tokyo Food Safety Information Center»Good things to know» Maximum danger – Pufferfish prepared by a non-professional
As pufferfish contain a deadly poison, improper preparation will result in food poisoning and can lead to death. Do not attempt to prepare pufferfish unless you are a profession and do not allow other non-professionals to attempt to prepare pufferfish.
Pufferfish toxin is deadly
Pufferfish toxin causes paralysis, resulting in difficulty breathing. There is no specific medication for treating pufferfish toxin and pufferfish toxin is characterized by its extremely high fatality rate.
Symptoms of pufferfish poisoning
Pufferfish poisoning proceeds extremely rapidly, with death occurring around four to six hours after eating pufferfish.
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Between 20 minutes and 3 hours after eating, numbness begins to occur in the lips, the tip of the tongue, and the fingertips. This is accompanied by pain such as a headache or stomachache and may also result in continuous and violent vomiting. A person experiencing pufferfish poisoning will totter or stagger when attempting to walk.
- Before long, sensory paralysis, slurred speech, and difficulty breathing will occur. Blood pressure will also drop.
- Thereafter, total body motor paralysis will occur and the sufferer will become unable to even move a finger.
- Consciousness remains clear until immediately prior to death. Once consciousness is lost, the heart and breathing will stop, resulting in death.
Cases of food poisoning due to pufferfish in the last 10 years (nationwide)
Year | No. cases | No. patients | No. deaths |
|---|---|---|---|
2006 | 26 | 33 | 1 |
| 2007 | 29 | 44 | 3 |
| 2008 | 40 | 56 | 3 |
| 2009 | 24 | 50 | 0 |
| 2010 | 27 | 34 | 0 |
| 2011 | 17 | 21 | 1 |
| 2012 | 14 | 18 | 0 |
| 2013 | 16 | 21 | 0 |
| 2014 | 27 | 33 | 1 |
| 2015 | 29 | 46 | 1 |
Total | 249 | 356 | 10 |
The fatality rate (the percentage of patients who die) of pufferfish poisoning is extremely high in comparison with other forms of food poisoning. The fatality rate for food poisoning due to pufferfish for the last 10 years (from 2006 to 2015) is 2.8%.
Types of pufferfish which have caused food poisoning in Tokyo
 Takifugu xanthopterus (Striped puffer) |  Takifugu snyderi (Vermiculated puffer) |
 Takifugu porphyreus (Genuin puffer) |  Takifugu pardalis (Panther puffer) |
 Takifugu poecilonotus (Finepatterned puffer) |
Cases of pufferfish poisoning in Tokyo (1993-2015)
Year | No. | No. | No. | No. | Source | Responsible party, etc. |
|---|---|---|---|---|---|---|
| 1993 | 1 | 7 | 5 | 0 | Takifugu xanthopterus (Striped puffer) liver | Restaurant (sushi) |
| 1995 | 3 | 1 | 1 | 1 | Takifugu pardalis (Panther puffer) liver Fished | pufferfish |
| 7 | 1 | 0 | Pufferfish (species uncertain) | As above | ||
| 5 | 1 | 0 | Pufferfish (assumed) | As above | ||
| 1996 | 2 | 5 | 2 | 0 | Takifugu pardalis (Panther puffer) miso soup (liver) | As above |
| 2 | 2 | 0 | Takifugu porphyreus (Genuin puffer) stew | As above | ||
| 2000 | 2 | 8 | 2 | 0 | Takifugu snyderi (Vermiculated puffer) and Takifugu pardalis (Panther puffer) stew (liver) | As above |
| 1 | 1 | 0 | Pufferfish (species uncertain) | As above | ||
| 2001 | 2 | 1 | 1 | 0 | Takifugu porphyreus (Genuin puffer) ovaries | Found pufferfish |
| 1 | 1 | 1 | Takifugu poecilonotus (Finepatterned puffer) liver, etc. | pufferfish | ||
| 2003 | 1 | 1 | 1 | 0 | Takifugu rubripes (Ocellate puffer) liver soup (souvenir) | Household |
| 2007 | 1 | 1 | 1 | 0 | Pufferfish dish | Restaurant |
| 2008 | 1 | 1 | 1 | 0 | Takifugu pardalis (Panther puffer) liver | その他 |
| 2011 | 1 | 2 | 1 | 0 | Takifugu rubripes (Ocellate puffer) liver | Restaurant |
Note: No food poisoning due to pufferfish occurred in 2004-2006, 2009, 2010, and 2012-2015.
How does pufferfish poisoning work?
The substance which causes pufferfish poisoning is called tetrodotoxin and is found in the liver and ovaries of pufferfish, as well as the skin and muscles in some species. This poison does not get destroyed during normal heating as part of cooking. Tetrodotoxin is extremely deadly and is said to be 1,000 times stronger than potassium cyanide.
The amount required to kill a person is aid to be around 10,000 mouse units. Assuming 1,000 mouse units of poison per gram of pufferfish, just 10 grams is enough to cause death.
The liver and ovaries of pufferfish exceed 10,000 mouse units per gram, meaning the tiniest amount will cause poisoning and can lead to death.
<Memo>
Mouse units are the unit used to represent the amount of pufferfish toxin, with one mouse unit equaling the amount of poison required to kill a 20 gram mouse in 30 minutes.
The amount of poison from ingested pufferfish is calculated as the amount of poison per gram for the part of the pufferfish eaten (mouse units/gram) × the amount eaten (grams). If this amount exceeds 10,000 mouse units, it can lead to death.
Pufferfish preparation is dangerous
As which parts are poisonous depends on the species of pufferfish, the ability to tell different pufferfish species apart is essential in pufferfish preparation. Many pufferfish species closely resemble each other in outward appearance, and some of these species contain poison in their muscle tissue.
For example, the edible species in the Lagocephalus genus and the Takifugu poecilonotus (Finepatterned puffer) closely resemble the poisonous Lagocephalus lunaris and Takifugu alboplumbeus. These latter contain poison not only in their livers but also muscles and skin and have resulted in accidents in the past.
There are other pufferfish species that resemble each other and, as shown in the able below, the parts which are poisonous differ for each, making it extremely dangerous if one is not able to differentiate them.
Due to the difficulty in identifying species as noted about as well as changing poisonousness throughout the year and due to individual variation, professional knowledge and skills are required when eating pufferfish. Many cases of pufferfish poisoning have occurred in the past due to amateurs with limited knowledge attempting to prepare pufferfish.Family | Species | Muscle | Skin | Reproductive organs |
|---|---|---|---|---|
Gray to black skin with no distinct pattern | Takifugu porphyreus (Genuin puffer) (adult) | Edible | Not edible | Edible |
Takifugu stictonotus (Spottyback puffer) | Edible | Not edible | Edible | |
| Takifugu flavidus (Towny puffer) | Edible | Not edible | Not edible | |
Takifugu obscurus | Edible | Not edible | Edible | |
Speckled body; species closely resemble each other | Takifugu snyderi (Vermiculated puffer) | Edible | Not edible | Edible |
Takifugu vermicularis (Purple puffer) | Edible | Not edible | Not edible | |
| Takifugu porphyreus (Genuin puffer) (juvenile) | Edible | Not edible | Edible | |
Takifugu niphobles (Grass puffer) | Edible | Not edible | Not edible | |
Takifugu poecilonotus (Finepatterned puffer) | Edible | Not edible | Not edible | |
Takifugu alboplumbeus | Not edible | Not edible | Not edible | |
Takifugu pardalis (Panther puffer) | Edible | Not edible | Not edible | |
Has a silvery white and lustrous belt on the side of the body | Lagocephalus gloveri (Brown-backed toadfish) | Edible | Edible | Edible |
Lagocephalus wheeleri (Blowfish) | Edible | Edible | Edible | |
Lagocephalus inermis (Smooth-backed blowfish) | Edible | Edible | Edible | |
Lagocephalus lagocephalus (Blueback puffer) | Not edible | Not edible | Not edible | |
Lagocephalus lunaris (Green toadfish) | Not edible | Not edible | Not edible |
Note: Fishing areas and processing methods are restricted.
Avoiding pufferfish poisoning
It has long been known that pufferfish contain deadly poison. Pufferfish may be an appealing food, but it is also important to remember that one can lose one’s life depending on how the fish is prepared. Preparing and eating fished pufferfish or pufferfish received from someone else without the proper professional knowledge is extremely dangerous.
Internal organs such as the ovaries and liver in particular should never be eaten, regardless of pufferfish species. Specific, professional knowledge and skills are required in the preparation of pufferfish. Please only consume pufferfish prepared by licensed professionals.
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