Not a problem.

Check the library for articles on feeding and Green Spotted Puffer general care.
Not many puffer will turn up their noses to clams, mussels or shrimp. You can get them in the seafood section of your grocery store and defrost them as needed in a cup of tank water. Freeze the remaining to save them for later.
You can purchase a liquid garlic in a local fish store or chop your own fine cloves and roll the food in it. I think you should try the mussels or clams first before the garlic. You will probably have luck seeing as the seafood is so pungent as is.
A liquid vitamin is good for any diet for fish. I use Gel Tek vitamins that are readily available in the US at a good price. You can find them in your local fish store or online.
What type of water is your friend in? An ample setting would be medium brackish to marine which is about 1.012-1.022 salinity. A hydrometer can help you test your salinity. Those can be purchased at your local fish store as well. The recommended tank size for them is 30 gallons as well. If he is a baby (1 inch or smaller) you can work your way up to something bigger but keep on the water changes if the tank is smaller. You want to do about 50% + per week of water changes to lessen the bio-load.
Like I said, read the article because it will give you lots of general information to help. We can clear up anything else you need here.

What is the new little puffers name?
Oh and welcome to the forum. Better late than never eh?
