Dwarf puffers need more than one gallon per fish. They will need at least 3 gallons per puffer, but most will suggest 5 gallons/puffer. You will also need to break up the line of site and have plenty of hiding places to escape to if there's a fight. Dwarf puffers (freshwater) enjoy each other's company when young, but will quickly get territorial as they age. Also, don't keep anything in the tank with any kind of puffer that you aren't willing to lose. Some have said they keep otos with puffers, but this isn't always successful. My puffers are alone in their 10 gallon tank, except for a few ghost shrimp and snails...which always end up becoming luch after awhile.
