Which fish is famous for inflating its body when threatened?

Pufferfish are famous for inflating their bodies when threatened.

Many pufferfish rapidly swallow water, and sometimes air at the surface, expanding into a much larger and more difficult-to-swallow shape. Their skin can stretch, while reduced or modified scales help preserve the rounded form. This response makes them a poor target for predators that rely on swallowing prey whole.

Pufferfish belong chiefly to the family Tetraodontidae. The common name covers many species, including freshwater and marine members. Their close relatives include porcupinefish, which also inflate but usually have prominent spines.

Inflation is not their only defense. Many pufferfish contain tetrodotoxin, a powerful neurotoxin, in parts of their bodies. Toxicity varies by species, population, diet, and body tissue, so the fish should never be treated as safe to handle or eat without expert preparation.