What are some fish that are compatible with a red tail shark, a discus, silver dollars, and tiger barbs?

i dont have the discus yet but i might get 1. i was thinking of an amazon leaf fish, or a species of goby. i will feed them brine shrimp(frozen) if i hav to even rosy red minnows as long as i dont have to only feed them rosy reds. i was also thinking maybe a cray fish.