Feeding my eel

So I just bought a peacock eel. I saw him a bit the first day but he wouldn't eat then. Since he has disappeared. I have sand as a substrate so I assume he's hiding in there somewhere. Anyways my question is how am I supposed to feed a fish I never see? I tried putting a sinking pellet in after lights out, although I still couldn't see the eel, I was kind of hoping maybe he'd come out at night and find it. That or it would just dissolve. *sigh*

:help:

Thanks for the suggestion, that should be good for keeping them from the silver dollars, thanks.