I don't see why not. They really don't have the best eyesight, so if at all possible you should put the food very close to it. Fish flakes should be good though, just keep an eye out and make sure it's eating.
My tanks (so far
5.5 gallon Planted Dwarf Puffer tank (2 Dwarf Puffers and a lot of RCS!)
16 Gallon Planted
(GBR pair, 3 amano shrimp and a whole bunch of snails!)