For fresh puffers......you could do a species only tank of Dwarf Puffers in the planted 30 gallon. The general rule is 5 gallons per puffer. They also do well with otos as a bottom feeder if you want something to go with the dwarfs.
For a single fish tank, the arrowhead or congo would do nicely in a 30 gallon. They are lurkers so they won't move much but they are nice oddball fish. They also like to bury themselves in the substrate so a planted tank may not work with them.
Your other puffer options are brackish water puffers.
You could do one Green Spotted Puffer. Their max size is 6 inches. They require high brackish to marine as adults.
You could also do two figure 8 puffers. They max out at 3 inches and require low end brackish for life.
I personally love the lurkers for their behaviors. It's fun to watch them bury themselves. But if you want personality....I'd go with the figure eights or the GSP. Both of these species are fairly interactive with their owners. The congo and arrowhead are personable enough but they do a lot more sitting around than the others.
Food requirements would be snails, shrimp, bits of clam or mussel, blood worms, etc. If you only want to feed pellet or flake, forget it, these aren't the fish for you. They will not eat it. Also, they are scaleless and very sensitive to ammonia and nitrite. They are high maintenance. If you wanna see pics just put the names I gave you into google.