We've all seen images of an adorably puffed-up pufferfish, but in reality, divers and divemasters do real harm when they cause these fish to puff up. ... Unfortunately, while puffing up can successfully discouraging predators, it also can be quite harmful for the pufferfish, sometimes leading to death.

Do puffer fish die when they puff up?

When a puffer fish puffs up, it takes in water to increase the size. This violently forces the puffer's organs to be pressed to the side, inside the body causing the organs to flatten. This creates an extreme amount of stress for the puffer fish. In some cases the puffer fish dies from this stress.

Does it hurt pufferfish to puff?

Even though they sometimes do it just to stretch, puffing up often can be stressful for a puffer. So, it's best if they do it only when they need to. This behavior isn't a puffer's only means of defense. Most puffers are toxic to eat.