Psh. Betta are tough too.
Not gonna start a stupid argument about that though.
I could do 15 gallons, but I guess I won't. I think I'm just going to take the gobies back to the store today and get this brackish thing out of my head for now. The brackish water is really what's best for them and I feel bad keeping them in fresh.
I don't know, I just got the idea after reading our TFK profile on them, and reading that puffers and gobies are tough enough to withstand each other really well.
My last idea is 15 gallons, with the gobies and celebes rainbowfish in brackish. But I'll probably throw that out too.
I've always read that watching gobies squabble is the most amusing part of owning them. They are really weird, sometimes I see them swimming together peacefully, sometimes they sit at opposite ends of the tank, sometimes they chase each other around. I've yet to see physical biting.