I can't see any harm in it.
I always try to replicate a critter's natural diet. I know silversides are a common food and I don't know if they are a saltwater fish. But I'd always try to feed my triggers, eels and puffers a very wide variety of meaty saltwater specific species of foods. NO GOLDFISH!!!!!! That always bothered me, but it seemed perfectly normal to other people.
That's one of the fun aspects of this hobby - trying to replicate a creatures natural habitat in every way, shape, and form. From the scenery and environment to light cycles to food and tankmates.