why do puffers put one or both pectoral fins into the gill opening(s)? I've had more than one healthy puffer do this. my dogface puffer is doing it now. not in any distress, just sitting on the magfloat with one fin completely inside the gill opening. once he started to swim, the fin came out. the first time I ever saw this, it freaked me out. since then, I have seen other puffers do it.