Actually, there are over a dozen different species of puffers that are all often grouped together as "dog faced puffers) and yours appears to be Arothron nigropunctatus or possibly a meleagris, ", which reaches about 11" at full growth (they are relatively slow growers, even though they eat LARGE portions)
The reason many people don't recommend mixing them with triggers is that thay are actually somewhat shy (except at feeding time) and literally WON'T fight back with almost anything.
Ours in named "Puppy" and we've had him for almost 2 years, now about 4", from the 1" when we got him.
These guys are also somewhat nocturnal in their habits, especially when house with more active fish, and a few krill or some shrimp right after lights out will often ensure that they get addequate food.