In certain species, the internal organs, such as the liver, and sometimes the skin, contain tetrodotoxin, and are highly toxic to most animals when eaten; nevertheless, the meat of some species is considered a delicacy in Japan (as 河豚, pronounced fugu), Korea (as 복, bok, or 복어, bogeo), and China (as 河豚, hétún) when prepared by specially trained chefs who know which part is safe to eat and in what quantity.

Other pufferfish species with nontoxic flesh, such as the northern puffer, Sphoeroides maculatus, of Chesapeake Bay,[2] are considered a delicacy elsewhere.

[3] The species Torquigener albomaculosus was described by David Attenborough as "the greatest artist of the animal kingdom" due to the males' unique habit of wooing females by creating nests in sand composed of complex geometric designs.

[7] Tetraodontiformes, or pufferfish, are most significantly characterized by the beak-like four teeth – hence the name combining the Greek terms "tetra" for four and "odous" for tooth.

[8] Each of the top and bottom arches is fused together with a visible midsagittal demarcation, which are used to break apart and consume small crustaceans.

The notably missing bone and fin features are due to the pufferfish' specialized defense mechanism, expanding by sucking in water through an oral cavity.

[9] Pufferfish can also have many varied structures of caltrop-like dermal spines, which account for the replacement of typical fish scales, and can range in coverage extent from the entire body, to leaving the frontal surface empty.

Its tail fin is mainly used as a rudder, but it can be used for a sudden evasive burst of speed that shows none of the care and precision of its usual movements.

The dwarf puffers court with males following females, possibly displaying the crests and keels unique to this subgroup of species.

In 2012, males of the species Torquigener albomaculosus were documented while carving large and complex geometric, circular structures in the seabed sand in Amami Ōshima, Japan.

It is believed to spawn in bays in a similar manner to saltwater species, as their sperm was found to be motile only at full marine salinities, but wild breeding has never been observed.

Xenopterus naritus has been reported to be the first bred artificially in Sarawak, Northwestern Borneo, in June 2016, and the main purpose was for development of aquaculture of the species.

They can survive on a completely vegetarian diet if their environment is lacking resources, but prefer an omnivorous food selection.

The oldest known pufferfish genus is Eotetraodon, from the Lutetian epoch of Middle Eocene Europe, with fossils found in Monte Bolca and the Caucasus Mountains.

[24] Pufferfish tetrodotoxin deadens the tongue and lips, and induces dizziness and vomiting, followed by numbness and prickling over the body, rapid heart rate, decreased blood pressure, and muscle paralysis.

Cases of neurological symptoms, including numbness and tingling of the lips and mouth, have been reported to rise after the consumption of puffers caught in the area of Titusville, Florida, US.

[29] Treatment is mainly supportive and consists of intestinal decontamination with gastric lavage and activated charcoal, and life-support until the toxin is metabolized.