Will catfish eat small crustaceans.?

Like really small, not a shrimp, like water fleas and copepods. I'm planing on feeding all my fish these crustaceans, but I have these two nocturnal raphael catfish. My substrate is rather large as pebbles opposed to gravel, so I was thinking that the crustaceans would mill around in the cracks safe from the other fish, then the catfish can pick them up after dark.