Gentamycin Sulfate is probably the strongest antibacterial in existence. It is a stronger version of Kanamycin Sulfate and is designed for resistant gram negative bacteria, including septicemia, fin and tail rot, and to bacteria where other antibiotics fail.
Gentamycin Sulfate carries a high level of toxicity on the kidneys and is ideal of a last resort antibiotic.
A full course of treatment is defined as treating once and leaving in the water for one week. If needed a second round is tolerable.