I believe these are a Brackish to Marine species, but are often imported as juvenile Freshwater Puffers. I could be wrong. They are definately a seasonal fish, and offered at a very low wholesale price when in season. For the last few years, I have noticed a short time frame in which they will become abundantly available. If I remember correctly, they are suppose to be somewhat peaceful.. Just like most people who keep puffers without proper research, these puffers likely end up being miscared for, just like GSPs.
I will try to get some more info tonight when I get home from work..