Tetraodontoxin is found to be a product of a symbiosis between its host and a tetraodontoxin-producing bacteria The host readily accepts the bacteria for defense against preadators in exchange, the bacteria is provided with food and a home. This is proven as many captive bred and raised puffers do not possess this lethal toxin (This does not mean that you should eat your puffer!) Its host does possess a certain degree of immunity to the toxin. There are certain fishes like boxfishes which releases toxins into its surrounding when stressed.
In Japan, pufferfishes are a delicacy and are known as fugu and have to be prepared by specially licensed chefs. The toxins in puffers lie in their skins, liver, and many other organs which the chefs have to skillfully remove. However, casualties of a result of eating puffers are reported to be above 100 victims annually. There is no known antidote for this toxin. Only a milligram of Tetraodontoxin is required to kill a human. Approximately 50% of those who ingest this toxin and receive treatment will not live to tell his experience.
The toxin can take effect from anywhere ranging from a few minutes to hours.
Symtoms of the poisoning includes weakness, dizziness and later on paralysis and breathing problems. If not treated immediately, victims are likely to die. Generally victims who survive the first day will. The best treatment available is using a intravneos drip and activated carbon to absorb the toxin.