I'm assuming you mean dwarf puffers?
Quick answer, most likely no. The puffers will most likely kill the convicts once they start to reach sexual maturity. Dwarf Puffers will kill fish much larger then themselves by harassing them constantly.
In a 30 gallon tank you could probably have up to 6 puffers, but you want 2 females per male, and a complicated aquascape so they can all hide when needed and have their own territory.
Ottocats (95%) and sometimes ghost shrimp (50%) are the most common tank mates for dwarf puffers, although each fish is an individual and some have been known to put up with other tankmates.
