The puffer puffed!

I was watching my puffers before bed, and they were all hanging out on one side of the tank. All of the sudden Bug got huge! She was like atleast twice her normal size! She couldn't really swim though and started to get pushed around by the current so she deflated. I don't think it was bad for her because she did it by choice not because she was afraid of getting eaten.

The territory issues are getting worse, it seems as though Bug has claimed all the space that is not the little one's. This morning I found Puff pushed up against the wall in a corner, and every time she tried to leave Bug would chase her back in. Its possible that bug has just moved her area because, when Puff went into the back left corner(which was Bug's) Bug didn't seem to mind.