Also, if you had checked the "Shrimp Varieties" page, you would have seen that there is a species on there that is commonly called "ghost" or "glass" or "grass" shrimp that breeds in freshwater.
The most commonly found "glass" or "ghost" shrimp are very short lived (a few months). And yes, they're sold as "feeder" shrimp. With a short lifespan, they'll reach reproductive maturity quickly, and have a faster turnaround time for breeders. Lots of offspring, quickly mature, make lots more offspring..... good candidates for "feeder" animals.