Where can I find a Freshwater shrimp similar to Brine Shrimp?

I need to build a self sustaining biome for Biology cl, and I've worked out what I need. My science teacher mentioned some sort of shrimp similar to brine shrimp (because i can't revamp my freshwaterenvironmentt to saltwater) but I need to know what they are called and where I can find them. I looked into sea monkeys, but they can't survive in freshwater more than a few days. Care to help me out? I need them to be about the same size and eat algae or water plants. please help me!!!