Take out the botia!
Yeah, the botia will nip the betta's fins until the betta no longer exists.
At least, that has been my experience: I have tried various botias in order to keep an invasive snail population under control, but the botias of every type have eventually gotten a taste for my bettas' fins. And this is in a tank with a little elbow room (29 gallons).
You can definitely keep other fish with your betta. Just don't get fin nippers (e.g., botias) or intelligent, more aggressive fish (neither S.A. nor African cichlids have ever worked with my bettas). Get stupid and/or peaceful fish. I have had success with many varieties of tetras, for instance, as well as rainbow fish (even the largest of these has never given my bettas trouble).
Good luck--but get that botia out of there before the beta loses all his fins!