There are two dwarf puffers,
C. travancoricus and
C. imitator, so you could try either of those in ten gallons. The second species is fairly uncommonly traded, but not impossible to obtain. While
C. irrubesco can live in 10 gallons, my repeated experience of this species is that it's nervous and shy in confined spaces. Much better to have 30 to 40 gallons and keep a group of 2-3 pairs than to try and keep a singleton or a single pair in 10 or 15 gallons.
C. lorteti is less retiring and may adapt better to small tanks, but I haven't kept this species for 20 years and can't really remember much about it! It is very aggressive though, so 10 gallons would be for a singleton, not a pair.
Other small puffers include
Tetraodon cochinchinensis and
Tetraodon erythrotaenia, but they both need at least 20 gallons.
Cheers, Neale
Gotchya, yeah I was just curious as to the puffers well being. Are there any other species of Fresh water puffers besides the Indian Dwarf puffer? (I have one indian dwarf puffer in my 10 gallon, but might be getting a 5-8 gallon tank only for him and 1-3 ottos)