Officials in Gamagori activated the town's emergency loudspeakers - "intended for use in case of North Korean missile attack", notes The Times - to warn the population about the mistake, and to appeal for the recall of the fugu.
While three of the five packages sold have been found, two others have yet to be recovered.
The fish, known as fugu, is an expensive winter delicacy but requires a license to prepare because of the dangers of mishandling. But the fish's skin, intestines, ovaries, and liver contain the poison tetrodotoxin, which is 1,200 times deadlier than cyanide.
The officials are using loudspeakers, which are used to make announcements during an quake and other disasters, to alert residents. Eating it could potentially end up in paralysis, coma, or death.
"Three packages will be retrieved today, but we still don't know where the remaining two are". And there is no antidote to this poison.
Between 2005 and 2015 in Japan there were 11 deaths as a result of eating the fish while 359 people were treated for fugu poisoning.
Several deaths are reported most years in Japan - although the number has dropped dramatically in recent decades - while dozens of other unlucky diners suffer from non-fatal symptoms.
"In Japan, we were eating fugu 8,000 years ago, and many people died because of the poison", chef Masato Sawahara said, as quoted by Prestige.