Try some mealworms. My silver really loved those. You get the benefit of the movement without the chance of disease that you would with feeder fish. Really good for the aro too. Mine went from 6 in to 18 inches in less than a year.
I musta had one of the non picky eater types of silvers. Mine would eat flake, pellets, bloodworms, mealies, and basically anything he could get his huge mouth around.