Dredge fish feces out of tanks nicer than most people's apartments
$$: $35,000--$85,000.
The upside: Join Aquarist Paradise, which describes itself as "a global community of aquarists that share a common bond: our passion for fishkeeping . . . and our desire to share our knowledge/experiences with like-minded aquarists."
The downside: Fish mung.
The dark side: Fish die horrible deaths with great regularity, often eaten by their associates.