I would be skeptical of this product only because the constituents are not listed.
Can anyone who has a bottle list the ingredients?
As training to be a ND, I should be at least vaguely familiar with some of them.
Herbal products are usually not too selective, but can be even more effective than pharmacuticals. If it will kill the ich, it will likely kill the beneficial bacteria as well,
something tea tree oil would likely do.
Therefore, I wouldn't use it in a main tank, but would use this product before
using a copper or formaldehyde based treatment in the QT.
As for ich, I've heard that by the time you can see it on the fish, medications are usually not too effective anyways for saving the life of the fish; you may
have to resort to fresh water dips. Sorry about the loss of your fish.