Ok, I just did a search on google for lifespans of puffer fish and finally find a question of lifespan. One guys asked if 2-3 years of age was old for a puffer and the person said NO. It has been reported that people have kept puffers for as long as 20 years.
A point of interest that he gave though, was that Public Aquariums keep records of such information.
So, maybe if she called a public aquarium they could help her out with some info on the lifespans of puffers.
It's a thought! I'll also keep check my post over there.