The common name I'm more familiar with is green spotted puffers, I am sure that they're the same as green dot puffers.
It is in general agreement that GSPs are a brackish-water fish as juveniles, and slowly swim into full marine waters when they're adults. That means that it is recommended that you start them in a brackish tank and slowly raise the SG until the water becomes marine. I'm not sure of a proper timetable for this, but many people in the Oddball's Institute have GSPs and know how to do this properly.
Their max size is generally 17.0 cm in most sources you consult.