Any small tetra would work. Since its only a 12 gal, the biggest fish i would out in that to accompany the betta would be platies. Bet setup that i can see for a 12 gal would be a pair of platies, the one betta, and a school of 6-7 tetras, and one otocinclus.

Gourami's are related to betta's and are also territorial. The bigger gourami would probably end up nipping off the bettas tail, most will get to big for your size tank anyways.


heres a few good links for further info.

http://www.fishinthe.net

http://www.myfishtank.net

http://healthybetta.proboards19.com/

good luck with the new tank.