Emperor Tetra's Refusing To Eat Frozen Bloodworm And Frozen Brineshrimp

They sound like teenagers who, having discovered burgers, won't eat their nice healthy salads any more 

All you can do is persevere. They won't starve themselves to death. When they get hungry enough they'll eat whatever you feed them. Fish can go a couple of weeks without food so I wouldn't worry yet.

There are fish that will only eat live food, but I'm sure emperors are not among them.

Have you tried anyhting else besides the frozen/dried live fod and flake? Possibly get some pellets (only make sure they are the right size for the fish you have) and even peas to vary their diet a bit. I have yet to find a fish that doesn't like peas, even the carnivores. Cook them (or save some from your meal), squeeze the insides out of the skins and chop to get the right sized pieces.



Having said all that, I did once have a betta that ate the betta pellets I had. One day he refusd to eat them, and I had to get a different make to get him to eat again.