Beserkr, if you go for a figure 8 (F8 ) puffer your tank would be ok if on the 'minimum' recommended size side of things, but you'd need to turn the whole thing into a brackish water setup and that's not as easy as it might sound.
Here are some points:
1. You need marine salt to create brackish water.
2. You need a refractometer to measure the salinity of the water, aiming for 1.005 S.G. eventually once the puffer reaches maturity, increasing salinity gradually over time.
3. You won't be able to keep any live plants in the tank: the salt will cause them to rot, unfortunately. This means:
4. You have to be a very good housekeeper! You'll need to manually clean any algae you experience, since you won't be able to house other fish with the puffer in that size setup even
if you could find brackish-tolerant species (very unlikely). Shrimp & co., which might otherwise work, are a no-no because they'll be eaten by the puffer in all likelihood.
5. Feeding puffers is a messy chore! They need a diet of bloodworm and crustaceans like mussels, cockles, and so on (I sometimes feed clams but the puffers don't always 'bite'!). This is food which will rapidly decay and cause problems if you leave anything uneaten in the tank for too long. Snails are also
vital for filing down the puffer's teeth: if you let the teeth grow, you're in for DIY surgery and it's not a pleasant experience! The diet regime is also a little bit more difficult to manage than with other fish: how much and how often you feed a puffer depends on how old it is. The older it is, the less it needs to be fed (and the less often). E.g. for an F8 that's 1-2", I'd be feeding once a day. If it's 3"+ I'd feed once every other day.
I'm offering this info in advance, before you set your heart on one (because trust me, I know it's impossible to walk past a puffer in the store, they're just too darn cute!). That is, you may want to set up a nice community tank and get settled into that before you venture down the puffer fish route. They're not an impossible fish to keep by any means, but they may just be a little bit more challenging that you might be prepared for!
Very cute though, like I said
Dwarf puffers (DPs), however, are freshwater fish so you'd have no problems housing 2-3 in your tank (again, on their own really: puffers may look sweet but they can be mean little things, even DPs!).
