1. Ten gallon for one; two need at least a 15; three a 20, etc.
2. They need live or frozen food and are very messy. Feeder snails are their favorites but frozen bloodworms will work, too. No pellets or flakes. I seem to remember one reason they need snails is to keep their "beaks" in good form but I could be wrong.
3. They also require a filter and a heater as they are very sensitive and, unlike hardy Betta, cannot handle temperature and parameter swings. Like shrimp, even .25ppm Ammonia or Nitrite can zap them.
4. Same as Betta their best temperatures are 78-80 to maintain long-term health.
5. Tank should be cycled before introducing a Puffer.
6. They are not easy keepers.
7. They need heavily-planted tanks.
IMO, more personality than Betta. I had one a few months ago but rehomed as it was too much work (see #6).
This is the late Hobbs' tank and very close to what a Puffer needs; however, more planting would be better.
Before I got mine I lurked on a Puffer Forum and talked to a fellow member about them. That member is no longer active.