The Puffer Forum

Could I keep a green spotted puffer and 3 dwarf puffers in a 30 gallon?

No.
GSP's need high brackish to saltwater conditions and require 30 gallons for one.

Dp's need fresh water, you can have 10 dp's in a 30 gallon.

But you cannot have both.

Is their any other freshwater puffer that can be kept in a 30 gallon with 3 DP's?

I wouldn't suggest mixing puffer species. I had a SAP in with my DPs & it was always getting bitten by them.

DPs are born with Napoleon Complex
Do you already have the DPs, or is this a new tank you have planned?

I do have the DP's, in a 10 gallon, but the 30 gallon is totally planned. I would prefer to move them in the 30 gallon because I have planned for something else to be in the 10 gallon.

With the DPs in the 30g, you could have otocinclus catfish to eat algae (be sure to supplement their food, and also not to add them for a few months after the tank is cycled), and a lot of shrimp (be sure to supplement their diet as well; even scavengers need to have regular feedings). The shrimp will add a surprising amount of life and detail. Ghost, Amano, and cherry shrimp would all be good choices. It's rare for DPs not to get along with these tankmates, even the shrimp. Plus, if the shrimp breed, they'll produce some nutritious, free meals for the DPs.

I've never had algae.

I like 'em because they're so darned cute. I'd have them, algae or no.