Interesting thread. I am a veterinarian and practice mostly with dogs and cats. I do fish stuff on the side. Mostly for friends but I do have a small clientele and hope to soon branch out into ponds. People have always asked me why I never went the zoo/aquarium route. My answer then and now is that I don't want to loose my hobby. Those I know that went the zoo/aquarium route lost their love for keeping home aquariums (become work). That being said there are some great opportunities in vet med for someone interested in working with fish: zoo/aquarium, aquaculture, biosecurity etc.
This would never happen in my dream scenario - the love I have for fish is boundless. In my dream scenario, I am in charge, large and in charge. I would skip to work and birds would sing on my shoulder.
If you loose your love for fish because someone pays you to do it, I'd argue that love was never really there. Unless you are abused somehow at your fish job or lose everything or what not.
Otherwise, BRING ON THE FISH JOB!
Remember when Larry sang "to dream the impossible dream" in three's company - when he sang at Jack's Bistro? Jack thought the crowd loved him, but Larry filled the restaurant with his co-workers, friends and members of his soft-ball team, remember that?
I'd sing that song on my way into work.