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 testes.

Most species are restricted to salt and brackish waters of the northwest Pacific, but a few occur more widely in the Indo-Pacific region or in freshwater of Asia.

[7][8] The eggs either float back into the water or may stay on land under rocks for a period, only hatching when again submerged by high tide.

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.

[citation needed] Apparently due to some unknown selection pressure, intronic and extragenic sequences have been drastically reduced within this family.

Since these genomes are relatively compact it is relatively fast and inexpensive to compile their complete sequences, as has been done for two species of pufferfishes (Takifugu rubripes and Tetraodon nigroviridis).

[13] As of 2012[update], there are 25 recognized species in the genus Takifugu:[14] * Fish that have edible body parts according to the Japanese Ministry of Health and Welfare