as a juvenile, it's going to need a meal asap.. odd that yours hasn't ate in a week. did you check your water parameters with a water test kit? typically catfish aren't picky eaters. With the wrong parameters or environment, it'll stress the fish and they won't eat.
also try earthworms.. they love them. if that doesn't work, I'd get a live feeder in there so he can get a first meal. you can worry about getting him a proper diet after he's eaten at least something
so have you checked out your water parameters? If the fish is disease free and the water is up to par with the catfish's preference, I don't see why it wouldn't have eaten by now. If you haven't, they're available at your local petsmart, petco, etc. I even saw them at walmart lol