depends on your puffer. some will, some wont allow tank mates. you may be lucky and get one that will allow it. unfortunately, a year from now your puffer might decide he doesnt like his friend anymore so its a risk
My sg is at 1.025. I just don't want to go spend alot on a clown to kill it. Do damsels and puffers get along? Just wondering because they are cheaper. I have zoa and mushroom coral and he dosent bother it.
LR displaces a lot of water and makes the tank hold a lot less then 30g. So I don't suggest you get any other fish, but trying tank mates is a good excuse to upgrade!
If I'm not mistaken (and I def could be) I believe in a FOWLR tank you need at least a 55g if you want to try tank mates for the occupants to be comfortable.
Another thing to think about is:
How long has your gsp been living by himself? If it's been a while he might be less willing to take tank mates. Also again it comes down to the individual puffer, and immature puffers tend to be more passive then older puffers.
I think im just gonna stick with him and add some more corals as he leave them alone. Hes been by himself since I got him about 3-4 mo. ago. I would try crabs but I put a shrimp in once and he wouldn't leave it alone until he finally killed it.