Aquatic antibiotics for an infection

If the wounds smells bad, try treating with an aquatic antibiotic like tetracycline. Use as directed to create bath water and submerge the crab several time a day for the duration of the prescribed treatment. Or just dab the wound with the treated water as often as possible for the full duration. Also separate the injured crab from the others and treat only its drinking water with the antibiotics. A good idea would be to mix a gallon of treated water and use that until the directions of the package say to add another dose, at which point, you would create a new gallon batch (or whatever volume is most convenient). Make sure the antibiotic that you choose is safe for invertebrates.
Please comment if you have had any experience with this.