Actually, male betta fish make excellent community fish with the right mix of peaceful fish. They do not get along well with nippy fish like barbs as they are likely to be harassed to no end, nor do they do well with swordtails because they are a brightly-colored fish similar in size to the betta and are often perceived as a competitor. However, male bettas do very well with smaller tetras such as neons and cardinals, as well as platies, guppies, and other small community fish. They cannot be put in with another male of their own kind, and if kept with a female he can cause injury to her in trying to spawn, but other fish do very well. In fact, I have often used male bettas to train my new fry to stay away from larger fish, because while they will nip at the babies they rarely chase them and their mouths are too small to eat them. Other than with competitors of their own species, bettas are one of the most peaceful fish for a community tank. I invite you to take a look at the overview of Betta Splendens I have amongst my hubs, and if it's not specific enough I'll gladly write a hub dedicated solely to tank mates :).