Good seafood is one of the greatest pleasures in life, and among fish lovers, fugu is a rare treat. The pufferfish, a winter delicacy, has moderately firm white flesh and a mild flavor. Its culinary notoriety is only matched by its legendary dangerousness. You see, the blowfish contains a deadly neurotoxin in its skin, liver, entrails, and ovaries.

And while cases of fugu poisoning are pretty uncommon, a supermarket in Gamagori, in the Aichi Prefecture, revived concerns around the fish when it accidentally sold five packages of fugu that included the toxin-packed liver. As of this story’s publication, the supermarket has recovered three of the packages, but the other two remain at-large.

Fugu shop
Fugu is strictly regulated in Japan, but accidents still occur a few times a year.

“We are calling for residents to avoid eating fugu, using Gamagori city’s emergency wireless system,” which broadcasts over loudspeakers located around the city, local official Koji Takayanagi told The Japan Times.

Fugu poisoning cases happen with a relatively low frequency. According to Japan’s Bureau of Social Welfare and Public Health, fugu poisoning isn’t always deadly. The government office reports that 354 people were hospitalized due to fugu poisoning between 2007 and 2016. Nine people died from fugu poisoning during that period.

Fugu in a fish tank in Kyoto, Japan
A tank of fugu pufferfish in Kyoto, Japan.

Lots of people eat the fish safely, though, and the reason for this is that the government has imposed strict regulations on fugu production. Sushi chefs must receive a license to prepare the fish in their restaurants, and grocery stores must have a license to sell it. Restaurants even have to keep the discarded guts in locked boxes to prevent dumpster foragers from becoming sickened. Production facilities, too, must be licensed. Fortunately, some farm-raised fugu are actually toxin-free varieties, but thrill-seekers still like to roll the dice on the real deal.

Japanese news reports that fugu livers were accidentally included in packages of fugu.

If you choose to eat fugu, you won’t have to wonder for long whether you’re safe. Symptoms of the fugu’s toxin, called tetrodotoxin, manifest relatively quickly, somewhere between 30 minutes and two hours after eating poisonous fish. This neurotoxin is a sodium channel blocker, which means it binds to voltage-gated sodium channels in nerve cell membranes and keeps them from firing. In short, it paralyzes you. Mouth and throat numbness or tingling are among the first signs of poisoning, and eventually your diaphragm becomes paralyzed, causing death by asphyxiation.

And while the toxin’s effects are irreversible, early detection could allow doctors to pump your stomach and absorb any undigested toxin with activated charcoal.

Interestingly, tetrodotoxin is actually produced by a handful of symbiotic bacteria, so some fugu farms have found that they can raise fish without these bacteria to produce toxin-free fugu.

So should you be afraid of fish? Probably not. But make sure that if you’re eating fugu that you go to a reputable restaurant or supermarket, and only eat it after you watch an enemy eat it.