I have a 10gal with one male beta. Is their anything that could go with my beta and not bother each other? He was very agressive when I first got him and have never tried to put anything else with him. He used to flare at the fish in the neighbor tank, but after having him almost 2 years now, he does not seem as agressive. He was originally in a 5 gal, but I have been doing some upgrading and switched him to a 10 gal this past week.