Hello,
A "Dwarf Rainbow Gourami" is the same thing as a Dwarf Gourami. Dwarf gouramis need at least a 20 gallon tank. Anything less and they can be quite a mean fish. A Honey gourami would much more suited for this set-up.
Here's some fish I came up with:
- Honey Gourami
Very peaceful community fish
- Sparkling Gourami
Nice small fish that likes to be in groups
- Endlers livebearers
Nice community fish that breeds really fast (Make sure to get all the same gender if you don't want babies)
- Pygmy Corydora
Nice community fish that needs a well established tank and a school of 4-6
- Chili Rasbora
Community schooling fish that needs to be in a school of at least 6
- Male or Female betta
Nice fish, but be careful when choosing tankmates.
- Dwarf Puffer
Peaceful FW fish that needs a nicely established aquarium, not really tankmate friendly though