If it were my tank, I would put a male betta in. I have had very good experiences with them in a community tank. They do prefer to have some floating surface plants and fake ones work fine. Often Petsmart has some pretty bettas for $1.99 and the longer I have had them, the more beautiful their finnage gets. Sometimes it takes them a while to get use to all the space they have, but soon they are swimming with the other fish.