My Emeralds get along with everything so far.... I have 1 that is getting huge, and he is content to sit up top and pick at rocks. Your shrimp is probably there, you just dont see him, I rarely see my Pep. And the Fire... We broke down a big tank not to long ago, and found one the guy had not seen for over a year....
And if you find the Skeletal Remains of an Emerald laying around, dont mean he is dead, he may have shed a layer????