Some pufferfish species also have spines on their skin to ward off predators. Even if a predator gobbles up a puffer before it inflates, it won't enjoy the snack. Most pufferfish contain a toxic substance that makes them foul tasting and potentially deadly to other fish. The toxin is deadly to humans. There is enough poison in one pufferfish to kill 30 adult humans, and there is no known antidote.
In Japan, they are called fugu and are a very expensive, delicious treat. They are prepared only by trained, licensed fugu chefs. Most puffers are found in tropical and subtropical ocean waters, but some species live in brackish and even fresh water. Some species of pufferfish are considered vulnerable due to pollution, habitat loss, and overfishing, but most populations are considered stable.