Red crystal shrimp? I assume that's what you mean by RCS...
MOST fish can eat shrimp, the only absolutely shrimp safe fish I can think of are otocinclus catfish, and maybe very small schooling fish like smaller tetras or rasboras. If you're willing to risk the lives of your shrimp, you could add a lot of other things, but you probably won't see the shrimp much, as they'll be hiding from predators.
Your plants need adequate lighting (every plant species has different preferences about how much light they like) and they would appreciate fertilizer, and if you want to get fancy some sort of co2 supplement.
If you use any sort of power filter, just cover the intake with a sponge so shrimp can't get drawn in to it.