Breeding shrimp for the aquarium set - cool. I remember a precursor to that, designed to separate foolish children from their money:

Not me though. I got the best cardboard Polaris submarine ever.
My current foolish endeavor is raising bamboo shrimp. They require brackish water for their early life and then a gradual change to freshwater eventually. I just hit the 1 month mark. All bamboo shrimp for sale are collected from the wild (that I know of!).