There are a lot of fresh water shrimp in the aquarium trade. I've kept some. Try searching "fresh water shrimp aquarium" or "fresh water shrimp breeding". All the ones I've seen are pretty tiny, so not much use for food. There are however some freshwater prawns that now populate the rivers of Hawaii, I don't remember where they were introduced from. Those could be a food crop, but I thing they need good water quality, making them a bad choice for closed system, high volume
aquaculture. That said, fresh water shrimp are expensive and a good income if sold to the aquarium trade. They can also be remarkably beautiful, depending on the species.