Dwarf Puffer (C. travancoricus) and that pic looks to be female, need at least 5g tank, freshwater, however, some of the puffers sold are brackish or salt this one is a freshwater species.
You keep them same as you do the male Betta splendens-a single fish per tank, mean little bugger with tons of personality just like the Betta.
They will blow-up/fill with air(not explode) and they need to always be kept under water so not to fill with air.
They need foods to help keep their tooth worn down too and common snail will help do this and one of their favorite foods, neat watching them attack and eat them. A lot of puffer keepers will also keep a tank just for raising snails and often it can be hard to get them to eat some foods, but not always..each are different just like the Betta.
Really cool fish to keep and only get about an inch and meaner than all get-out even to their own species
Also, be careful with copper based medication as they are a bit sensitive to copper and most chemicals for that matter.