A lot of fish won't start harassing others/show their true behavior until they're are a bit older.
Just because you have had it in a community until now, and so has someone else DOES NOT mean that it will stay that way.
Good examples are the Chinese algae eater and Black Ghost Knife.
Being your age, I know you'll ignore all this advice, but I suggest you at least read up extensively about dwarf puffers and then make your own decision.
"Aggressive."
"Best kept alone or with smaller fast tank mates."
"Otos are OK, slow moving fish will be nipped."
"Not recommended for a community."