Join Date: May 2008
Location: San Francisco, CA
When I was new to the aquarium world, people kept telling me it was okay to keep endlers with RCS. Little did I know these people were just trying to sell me a product so I would buy more stuff from them. So I ended up buying and mixing endlers (2 pairs) with 10+ RCS in a 20 gallon tall tank. Driftwood + Java fern all there. In the end, my RCS were wiped out before they could even breed. In a stable population of RCS, you can probably get away with it. But if you're adding them at the same time, I wouldn't recommend it. Guppies/Endlers (same thing) are pretty dense. They'll bully and pick at shrimp they can't fit in their mouths just to pick at it and eventually pry it apart.
They won't be able to decimate a healthy population unless the number of fish to shrimp ratio is super skewed. Just know that adult shrimp aren't safe with adult guppies.