pufferfish

[Isaacr]

What is the poison that pufferfish secrete, does it just kill humans

[incitatus]

Tetrodotoxin. Though there are quite a few pufferfish species, with different ones, this is almost certainly the one ou are thinking of. And no, its toxic to pretty much everything....I mean why would a fish develop a specific defence against humans? Unless its a cod its got much worse predators to worry about.