Hope your tang is doing better now.
You have to eradicate the ich. Ich isn't always visible. It may not show, he may not scratch, but rest assured if there are ich there, your fish is slowly being starved off of nutrients in its body.
freshwater dip would be ironic for tang, in my opinion. Imagine, when I acclimated mine back in the days, I had to let the plastic bag sit on the tank to equalize the temp, then I have to do a drip acclimation that would take between 2-3 hours. Tangs are very sensitive to change. Imagine shocking the poor tang in zero salt? Then shocking it back to salt water? That would be very stressful or even lethal to the tang. That's just my opinion, however.
would be great. Scoop your tang into a bucket with your current display water. Drip acclimate it for 2-3 hours into your QT
. Then start the hypo process. I do hope if you have a QT
, you maintained it while there weren't any patients.
Then do the hypo treatment. Now, if you have other fish in the display, you might want to remove them too, to starve the ich of host fish. Then treat the display if you don't have inverts.
the garlic will only serve as a suppliment for preventative measures. They may help the immune system of the fish so that no further bacterial or parasitic infections can result from the hypo stress and the ich stress. It isn't guaranteed to bullet proof your fish, but encouraging the immune system may help prevent further damage.
There were articles I read that other hobbyists are claiming that ich doesn't like garlic. Hey, it's like the dracula movie: both ich and dracula are blood suckers. If dracula hates garlic, the ich probably does too. However, no scientific evidence.
Remember, the stages of ich will mislead you if you depend on the visual. I do hope by now your regal is doing much better.