Oxytetracycline is the second broad sprectrum antibiotic to be released in the United States. It is a very popular antibiotic because it can be used to treat both gram-positive and gram-negative bacteria. The hydrochloride is 99% or higher active. Oxytetracycline is used to kill marine ulcer disease, mouth fungus, cold water disease and bacterial hemorrhagic septicimea. It is a good all around antibiotic.