It's probably carinotetraodon travancoricus (which is commonly sold as
a dwarf puffer). If that's the case, it's a true freshwater fish, not
brackish.
But yeah, it could be tough on the gentler tank mates.
Puffers and angelfish are a bad combination. Puffers are especially tough on
fish with long, thin, trailing fins, like angelfish and gouramis. They seem to
think those skinny fins are worms or something. A 1" puffer can terrorize an
8" angelfish.
Leigh
http://www.fortunecity.com/lavender/halloween/881/