Freshwater puffers are just that. If you are referring to carinotetraodon or the pygmy puffers, they are often found in soft acid waters, no salt required.. As to breeding: Lot's of live or frozen food & lots of hiding places (they can get nasty). Spawning is generally pretty straight forward when they are ready. However, ( & here is the bad news) The newborn larvae can be tricky to feed initially, they seem to very specific about what foods they will accept. I did see one report on breeding Siamese redeye puffers, C. LORTETI where the breeder claimed to have had success feeding live white worms strained through a handkerchief.
What species of puffer did you have in mind?