I put my puffer in the tank. As soon as he came out of the bag he decided to see what a powerhead was. So he stuck his face is the end of it. For like a week and a half he wouldn't move if the powerhead was in the tank. Now he is ok with it. So maybe something has scared him. Also puffers are nocturnal. When spike first came home he never swam around. he owuld get food and hide in the rocks. Then I was looking at the tank at night, and spike was a wild man. Swimming around and exploring. See if you turn the lights off if he is more active. just a thought.
Leopard