I think they just sell them in those tiny bowls so they can keep the males apart. If you put 2 or more males in an aquarium they will tear at each other until there is one, or none, left. They'll keep ok with regular fish in a regular sized (10 gallon+) aquarium. I think their life span is about 3 years. The female lived for about 1.5 years. She had a nice, deep red/purplish color.
I wonder if two females and one male can get along in the same aquarium...