The puffing is cool but you might want to try and figure out why he is doing it. I came back from a 4 day vacation to find my MBU puffed and swimming slowly. I don't know how long he was like that but he did not survive very long at all. My porcupine puffer only puffed twice. Once was when he ate a hermit crab that was dead. I was going for the net to fish it out and he got to it first. Once swallowed he instantly puffed and spit it out. It took a day or so for him to return to normal. The second time I came home from work to find him puffed in his tank dead. It does look very cool when they puff but in my experience it has never ended well when they do.