I think this goes back to the question we're asked in elementary school... "What do you want to be when you grow up?" And no kid says, "I want to push paper for a living." I think a better question is what you want to do, because the above question indicates that what you do to earn money is your sole identity, and we know that's not true. Individuals on this site have a common passion -- fishkeeping -- but everything else varies.
There is also the fact to consider that if you were a fish store owner, you may quickly become disillusioned and bored with that job, and wish that you had a higher-paying job which allowed you to keep regular hours and afforded you enough to live comfortably and enjoy the hobby of fishkeeping. Retail's no fun. In this "life," the life you've got, you have time to spend with your son, time to do what you enjoy, and maybe that's what you should focus on. Because the struggling fish store owner might trade with you any day.