sharker:
Sharks have natural immunities that far exceed that of normal boney fish and humans even. However if in a rare occasion you sharks do get sick from either parasites or bacterial or whatever... some common treatments are freshwater baths for 5 minutes, dropping the salinity below 1.014, in the cases of SOME sharks you can treat them with copper... however you should research whether you have a shark that can or cannot be treated with copper. Epaulettes cannot be treated that way. Another widely used method of killing parasites from sharks is the use of formalin. However with formalin you have to be very careful how much you use because it is a carcinogen.
Some other documented medicines you can use for bacterial infections are:
Ampicillin, Gentocin, Baytril, and Furacyn. Parasitic you can use Dylox or Droncit.
If you are truly worried about the health of your shark I suggest you buy a book concerning diseases and sharks. There are more than one available I'm sure.
Jim