hey check out this page, this is what I am talking about and why I was so confused over this fish. It says they do best in freshwater but they also list the lifesapn at 5 years perhaps that is why?
http://freshaquarium.about.com/cs/otherfish1/p/figure8puffer.htm
http://freshaquarium.about.com/cs/otherfish1/p/figure8puffer.htm