One of the saddest little (well, he was quite big) GSP's I've ever seen! I wanted to take him home and save him, but I knew better. And then I saw these, which they were selling as GSP's! I know I am not a puffer expert, but I believe these are Ceylon or Figure 8's or something...but def. not GSP's! 
Sorry, had to rant.
Anyways, thanks again for everyone's help here. Carlos is doing very will now, I think he's been in our home for about 3 months now. We are converting to brackish then marine. I just did a water change and now we are at 1.0004. He seems to be much more active and brighter ever since we have added salt to the water. The fiance is excited to go full marine, so we are working our way up.