The type of tetras that are kept as pets, including the bleeding heart, black line, serpa and lemon tetra, are generally undemanding. They can probably live in a fish bowl, but they should not.
Tetras love to live in schools and need plenty of room to swim around. One or two of these fish kept in a fish bowl are not going to thrive the way they should.
Tetras are alert and peaceable fish and they like to school with members of their own species and with other types of fish of the same size. Most also like vegetation in their habitat.