I have a puffer in an aquarium that seems a bit touched. When I first got it, it would not eat on its own, so I would have to grab it, and when it opens its mouth to suck in water to puff up, I would stick food in its mouth. Well it got used to that and evidentially its a game now. He will swim around and beg for food, but still wont eat on its own. So I put my hand in the tank and sometimes the fish will swim right into my hand, and start to puff up. As soon as I stick a piece of food in its mouth it starts to deflate and swims away...