I just got some antiparastite food for my shore shrimp ( made by Jungle and recommended by the seahorse people to feed feeder animals).
My plan was to feed them in their own container though since it's meant to kill worms so might also harm tube worms etc. in the main tank.

Other than that I really like Seachem products: StressGuard as a preventative and ParaGuard if they actually have something.