I think I figured it out.. I believe it to be Takifugu obscurus
Check out the picture below.. Notice the definitive black spot located at the dorsal fin., and near the pectoral fin. Also notice the white belly with the intense yellow line that divides the fish. Your fishes complete yellow and blotchy pattern might be due to lack of Salt, as they are to be a marine fish when they reach full size(40cm).. Also, the picture below shows a fish that is not alive, so it might of lost alot of that yellow coloration on it's back..
But as we all know, Patterns with Puffers can be completely random. The key is the definitive line seperating the white/yellow, the eye spots on both the dorsal fin and near the pectoral fin. The slender body shape also is most resembling the Takifugu family of puffers, more than any other species. I definately think that lack of salinity or long-term stress could of caused the pattern on your puffer to develop the way it did.. It is also hard to determine the age and size of the puffer below, which could create the contrast in pattern.. As they grow, they could gain more of that yellow coloration, or it could be from lack of salt.. Who knows. Also, notice the black splotchy eyebrows on your fish, and compare it to the black dot starting to form above the eye on the picture below. This pattern could just be starting to formulate on the Puffer below, especially if it is a juvenile specimen.
I could be wrong, but if you go to
this website it shows a picture for just about every species of Pufferfish. This is the one that came up the closest in all my search results. My 2nd guess would be the C. Psittacus.. but think it would have less yellow and more 'bands' as the common name 'banded parrot' fish implies just that.. Your's is more splotchy, and the ocellotus spots in the same locations as the Takifugu species is a big hint.
Hope that's the one!! Looks like he should be in a near brackish/marine tank right now..
