Slice a cube of tubifex worms into 1/3's and dampen a small rock and stick the cube to the rock and sink it. feed a bit of floating food while doing this to keep any fast swimmers occupied
I never felt that the cories got enough food in the tank with the danios, 5 young pandas died, I restocked with different adult cories but wehn it looked like they might starve, I got rid of the danios.
Dang danios would take turns harassing the cories, one would cirlce and bump them, then another would come circle and bump them, then another. They were scared to death. Good riddance.