Aquarium bacterial medications are medicines or antibiotics that treat bacterial infections in your fish. These include hemorrhagic septicemia, columnaris (called mouth rot or mouth fungus - it resembles a fungus, but is coarser and grey), dropsy, etc. Over-use of antibiotics can destroy beneficial bacteria and cause spikes in toxic ammonia, so we recommend quarantine tanks whenever possible, and avoiding use of antibiotics as all-purpose treatments.
Isolate afflicted fish or organisms in a quarantine tank as soon as symptoms are noted and medicate immediately. As with all fish diseases, the best prevention is regularly cleaning your aquarium, maintaining proper water conditions and avoiding fish stress.