My dwarf puffer is sick...HELP!!!

[PuffLuv]

Have you tested for ammonia, nitrite, and nitrate? What are you feeding them? In my opinion, you have too many puffers for that size of tank. I had a hard time trying to get mine to eat anything other than meaty foods(ie. bloodworms). Your biofilter probably can't keep up with this kind of bioload. Also, these little guys are prone to internal parasites, have a short lifespan, and can be quite vicious to each other and other fish.