I had the same thing happen to a betta of mine that was by himself. I started treating his bowl or tank what ever you have with Bowl Buddies for Bettas and gold fish. After a few water changes, and a bowl buddy added at each complete change, he is doing great and the holes are gone. It also took care of a ick problem I had with one of my fish. All my bettas are doing great, and seem alot better since I started using these tablets. Give them a try.