Sounds like a Spotted Puffer aka Guinea Fowl Puffer also Golden Puffer. Although a plain yellow color phase occurs, normally the brown-grey body is densely covered with white spots. Comes from the indo-Pacific, Red Sea areas.
You can also check out many Puff pictures if you go to my homepage (get there by clicking on man standing next to house).
[ September 22, 2001: Message edited by: Pufferlover ]