I need help with my green spotted puffer fish, please help?

You could aso get a fish catch container that petstores use (the plastic ones that hang off the side of the fishtanks.) That way you could catch your puffer without netting him (which is stressful to them and air is harmful to them) and hang it on the inside of the tank, which would separate the two puffers. Feed them individually and then release the larger one back into the tank. It would be a lot less stressful on all combined. The divider idea someone else had is also a good idea.