Unless you have the space for all of the fry from the moment they are born until they are sold, you should not be breeding your fish. Pet stores would probably not accept your fry because they usually have a source that they get their fish from already. Before you breed, you should have potential homes lined up already, if you do not have the space for long term housing of the fry.
Be responsible, and realise that you will probably spend more money breeding then you will make.
(like breeding dogs for example