^ I seriously doubt it... don't think any body commercially breeds MBU's yet, so its very very unlikely you'd find one that small for sale...
Any way, if you ask me it looks like it could be a Male Carinotetraodon irrubescoor or possibly Tetraodon cutcuti??? but a bit hard to tell with those pics since you can't really tell the color etc...
Otherwise, just check out the links for other F/W puffer profiles if you don't think its either of them???