Box fish have a simalar toxin that they can release into the water if stressed, but puffers can't release theirs, From what I've read all puffers contain at least a little toxin but amounts and concentrations vary greatly even among members of the same species. The toxin is found mainly in the skin,ovaries,and intestinal tissue but also in the fatty tissues. It kills by creeping parayisis, survivors report that they were aware the whole time. Puffing air can cause problems for puffers, I don't know why.