Hi, Rosie.
If you say "They" i suppose you mean the guys at your LFS.
"They" are experts in telling lies,halftruths and misinformation. :angry:
I'm glad you decided to investigate before buying.
Here's an article on the pig nose puffer.
I like this first line of this article:
The Tetraodon suvatii, commonly sold in the aquarium trade as the arrowhead puffer, Mekong puffer, pig-nose puffer or hog-nose puffer, is
one of the most vicious of all puffers. The suvatii is rapidly
growing in popularity due to the observable butchery involved in its natural eating habits.
www.wetwebmedia.com/FWsubwebindex/t_suvattii.htm
The puffer forum states it will be agressive towards other (puffer) fish.
So, no matter what your LFS tells you, and how sweet the pignose may look, i say do not buy him, unless you plan a single species tank.
Add their sensibility to ammonia and nitrites to their piscivore nature and you got yourself one bad tankmate for an oscar.
I've seen puffers swim up to a adult Oscar and bite a piece out of it's back, just because he was hungry.
Ugly sight.
Maybe someone else has got personal expierience and will give you different advice, but i say this puffer needs a single species tank.