Your fish doesn't need or even want "friends" he may tolerate tankmates but he wont necessarily like them. He probably wont interact with them much except maybe at feeding time when they fight for food. Just need to get that out of the way. Fish are not people. They dont get lonely.
Anyways. Cory cats are generally well accepted by bettas. Other non-bottom dwelling fish are a hit or miss. I have managed to keep mine with platies. I hear that neon tetras tend to work as well.
Last edited by Alex09; 12-17-2010 at 12:29 PM.