I'm going to be setting up a 178 RR tank that is 60.5" long x 24.5" wide" x 29" tall. What can I get for tangs. I'm starting to learn you can't get two of the same type of tang species, but here's the ones I want: Blonde Naso tang, Powder Blue or Powder Brown, Purple Tang, Yellow tang, Achilles Tang. What else? I know I need to pick between the Powder Blue and Brown - I heard the Brown's are hardier. Is that true? Are Tangs more susceptible to ich than other fish? What's the risk?