After I added 2 clown fish from the best pet store in the world

near my house I lost all of my tank within 3 days.

All of the fish would look fine one moment swimming and being active next thing I knew at the bottom rapidly trying to breathe. I self-diagnosed it as Velvet because I could not see any small spots. I guess it doesn't help that I tried to treat a few of them for ICH

, but down to my question. Will velvet stay in my tank and infect future fish, or will it effect my 2pepermint shrimp, My Crab, My Coral, Clams, Mexican Turbo Snails, or hermits. Thanks for any help.