Playmates For Your Puffer
Bumblebee gobies
Guppies (Poecilia reticulata)
Mollies (Poecilia latipinna, P. sphenops, P. velifera)
Platies (Xiphophorus maculatus)
Swordtails (Xiphophorus helleri)
Some puffers are left best isolated, they may think anything not another puffer is food. Some do play well with others. Many (people :) believe that only male puffers are aggressive, but I don't think it has been scientifically proven. Also, only about 10% of captured puffers are male, although I myself do not know how to sex puffers.
Other Brackish Fish
Scats (Scatophagus spp.)*
Monos (Monodactylus spp.)*
Archer Fish (Toxotes jaculator)
Shark Cat (Arius jordani)
*Juveniles are brackish, but adults are saltwater fish.
For more information about any of the above mentioned fish, please see my Links page.