"Black ick" is really not the same thing as Ick [or white spot disease]---which is the good news, cause black ick is not as deadly or contagious. The parasite is a flatworm and they like yellow fish, particualarly yellow tangs. The disease is also nick-named Yellow Tang disease. [You didn't say whether your tang was yellow or not, but I'm guessing he is?]
The meds you got is basically a waste of money, IMO, based on the ingredient list you provided...except perhaps the Vit c.
If this fish does not appear to be in the dying mode...still eating or trying to, swimming a bit....perhaps hyposalinity would be the best course of treatment rather than subjecting the fish to chemical treatment.
Hyposalinity: Over the course of a few days, gradually drop the salinity in you hospital tank to 1.007-1.009. Maintain this level for a week after all signs of diesease have disappeared, then gradually increase salinity back to normal. Leave fish in QT for one week to ensure continued health then, either return fish to main tank, or give fish a breif formaldehyde [formalin] bath, then return fish to tank. [If you hadn't already put your fish in the QT, I would have also recommended a formalyn bath before placing him in QT.] Since this is a "no-medication" treatment, you can run fresh carbon continuously ensuring that optimum cleaning conditions are maintained in the QT tank.
The upside to this treatment is that it works if your fish can live long enough while you are dropping salinity levels. Also, you expose your fish to no harmful chemical treatments.
If your fish is very sick, you can treat him in the QT tank with formalin [formaldehyde] added directly to the QT or use the copper treatment. NOT BOTH TREATMENTS AT SAME TIME!I would run the carbon filtration for a few hrs first to get rid of old med and clean up water as much as possible. Formalin and copper are oxygen depleting so you must maintain excellent water quality during treatment as well as good surface water ciruculation.
The chemical treatment is faster working than the hyposalinity, but you're exposing your fish to chemicals that can harm their organs....follow medication instructions exactly...more is not better with these meds....they can be deadly.
If you can get Zoe or Zoecon at the LFS, and your fish is eating, soak your food in this vit supplement. Remember tangs are vegetarian and need a diet very high in greenstuff--preferably seaweed.
Good luck!
[ April 21, 2001: Message edited by: Beth ]