Internal Parasites

Since all Green Spotted Puffers are wild caught there is always a high probability that newly purchased puffers will have internal parasites. It is recommended that all new puffers be treated for internal parasites (I.P.'s) before being added to a tank with other fish or inverts. Puffers who suffer from I.P.'s will have a "sunken in" belly, or look skinny. If left untreated I.P.'s can be fatal.
There are several ways to treat a puffer for I.P.'s. but I recently tried a product called Kusuri Wormer Plus For Discus. It's a milder medication that has worked wonders on a puffer I bought with a particularly bad case of IPs. It's impossible to overdose your puffer with this medication. When I use it I add a double dose directly to the tank itself (I dissolved the medication in a small bucket and then added it to the tank), and soak all my puffers food in it. I continued treatment for two and a half weeks and all my fish are currently parasite free and healthy. I highly recommend this course of treatment for any newly acquired puffers (even if they seem healthy- there's no harm in treating just to be sure).
Keep an eye on your puffer's condition, if necessary repeat the treatment. A healthy puffer will have a white, rounded belly, be active, and always begging for food.

For a more in depth article on treating Internal Parasite's see the article written by Amy J. here: Internal Parasites: Prevention and Treatment