It is not safe to touch a pufferfish because they contain tetrodotoxin, a potent neurotoxin that can cause serious harm if it enters the body through cuts or abrasions. Additionally, when inflated, their spiny skin can cause injuries. Therefore, for your safety, it is best to avoid touching pufferfish altogether.
Pufferfish puff up only as a defence mechanism when they feel threatened. They do not have a limit to how many times they can inflate in their lifetime, but they generally do so infrequently, only reacting when danger is near.
Pufferfish are poisonous, not venomous. This means their toxin, tetrodotoxin, is dangerous if ingested or absorbed through the skin, but they do not inject venom through bites or stings. Their toxin can be lethal if it enters the bloodstream.
Pufferfish puff up as a defence strategy to appear larger and more intimidating to predators. They fill their bodies with air or water and expose sharp spines, making it difficult and risky for predators to attack them.