No, heat basically does nothing for saltwater Ich, except to maybe speed its life cycle up and help it multiply. Copper or Hyposalinity in a QT are the only two methods to cure Ich. Adding garlic supplement to food helps the immune system, but is not a cure. Pair that with leaving your DT fallow for 6 weeks and you are Ich-free. Do anything other than that and you are not and it can (and usually will) come back. Doing those in a DT is not a good idea.
Tangs are very prone to Ich. Tangs in small tanks (less than 6 ft for most) tend to get stressed, which lowers immunity, which increases the possibility of getting stuff like this.
Read up on Ich. It's important to understand the life cycle, what works, or doesn't, and why. There are lots of great articles online. Don't be fooled, like many are, when the spots disappear. That is part of the life cycle, not a miraculous recovery. If nothing is done to irradicate Ich, it lives and multiplies.
