Louis The Fish by Arthur Yorinks

Louis is a butcher. He has a nice shop on Flatbush, with steady customers. He's "always friendly, always helpful, a wonderful guy." But Louis is not happy. He hates meat!
All his life he's been surrounded by meat. His grandfather was a butcher. His father was a butcher. His whole childhood, even his birthdays, revolved around meat. As a boy, he tried anything to escape--even a job after school cleaning fishtanks.
But that doesn't last long. Louis soon has to take over his parents' butcher shop. He grows ill. Business begins to fail. All seems lost. On one night, in fitful sleep, after uneasy dreams, Louis is changed in a profound and startling way and begins a happy new life.