Originally Posted by jetajockey
Don't keep which species together?
Look for low b/c grade shrimp, they are usually more affordable and I often see them around $2-3 each.
The OP said there were Green Crystals and Red Crystals. I'm assuming both are Caridina Cantonensis just different color variants. In which case, they will interbreed and result in a not so pretty baby.
I'm sure you know, but for less informed viewers out there, but selective breeding was the only way to get color into the Shrimp you see. Crossing a Green Crystal with a Red Crystal won't get you a Red, Green, and White colored Shrimp (although that would be awwwwesome). What that does do is basically breed out the color traits that were bred in over generations.
Now you know. And knowledge is power.