Betas breathe like other fish through their gills. They are comfortable in small bowls as their natural habitat is puddles and small ponds. A plant will consume the oxygen in the water starving the fish. The bubble nest they create at the top of the water isn't an effort to breathe but instead trying to attract a mate. Go to the pet store and get beta food. They are tiny pellets and feed him carefully so as not to overfeed him. Too much food is deadly to a beta.