Technically I believe both fish are water column feeders so the risk should be low, however I would never say it will be a sure bet. Is it a large tank with live rock? You can give it a try...if it fails, your triggers will enjoy the meal and it will not be a huge loss overall. What is the specific gravity of your tank? Do you have corals in there?
You could probably also try introducing some ghost shrimp to see if they go nuts over them or mostly ignore them. That might be an indication. But overall emerald crabs can lay pretty low.
They are in a 150 with liverock,sg is at 1.0021 and if ghost shrimp is the same as feeder shrimp,yea they love them.But im gonna give it a try,i just placed an order here and they giving me 2 emeralds for free.