My puffer setup is a 64l cube, 100w AquaOne heater, Fluval 104 canister, 70w MH light, C02 (not going at the moment as it needs a refill), 3 puffs and four Otocinclus. Plants are (and these are essential to stop them beating the snot out of each other when they see someone out of the corner of their eye) Valisneria, Hemianthus micranthemoides, Echinodorus leopard, Anubias and hairgrass that is missing the C02 and not growing particularly well.
Now before you hit the floor at what is on this tank it was previously set up as a more highly stocked planted tank. And if you choose your plants carefully you will not need this level of light, a twin 15w fluro fitting will allow you to grow quite a few things that will provide cover for your fish.
They will only eat live food, so they get blackworms, grindal worms, snails that are too silly to hide from them, daphnia and mozzie larvae. I have tried wingless fruit flies but they sit on the surface and puffs are sneak around looking at the bottom of the tank for critters rather than look for things that fall on the surface hunters.
I would go for a HOB filter as you cannot plant with a good substrate with an undergravel filter. AquaClear is my HOB of choice because you can load it up with ceramic noodles over the sponge whereas the other one has slide in cartridges that do not allow this.