I have just entered into the wonderful world of puffers
I've got 2 green spotted puffers in a 15g - sand substrate, mopani wood and assorted plants.
Some info:
Figure 8 Puffer
Size - 3" max
Min Tank Size - 30" x 15" x 12"
Water - Soft to Medium Hardness/pH7/22 - 26 Degrees
Diet - Carnivorous
Temperament - Aggressive (Species only preferred)
Green Spotted Puffer
Size - 7" max
Min Tank Size - 36" x 15" x 12"
Water - Hard/pH8/24 - 28 Degrees
Diet - Omnivorous
Temperament - Aggressive (Community only with similar size fish)
Dwarf Puffer
Size - 1"
Min Tank Size - 18" x 12" x 12"
Water - Soft/pH6/22 - 28 Degrees
Diet - Carnivorous
Temperament - Aggressive (Best kept in a group)
This is what my research turned up about the three most common species, hope this helps at all.