I suggest a larger tank with heater and filter, as that betta does not look happy. That tank might be alright for temporarily, but a betta in a bowl is not a good idea.
Get a larger tank, 5gal+ would be excellent, put a great many number of plants in it, along with heater and filter, and then you may possibly have some other fish in with your betta, eg mollies or platties or tetras possibly. I wouldn't go near barb, guppies or most cichlids, as your betta mightn't look too pretty after a while and the guppies it'll just kill for whatever purpose suits it.