Amoxicillin is an antibiotic related to penicillin that stops bacteria from multiplying. The use of amoxicillin for fish can treat several bacterial infections caused by water in fish tanks that is too warm or poorly maintained. When a fish is sick or injured, it allows the bacteria to flourish, which may kill the fish if not treated quickly. The aquarium owner can use amoxicillin for fish that show symptoms of fin rot, red pest, tuberculosis, scale deformities and dropsy.
Fin rot is a common disease seen in gold fish and neon tetras. It begins with whitish sores on the fins that may turn orange or yellow in a few days and spread to the gills. Affected fish might develop mucus that impedes respiration and can cause death. These fish might stay at the top of the tank or at the bottom as they try to breathe; they also may stop eating if the bacteria spreads to the mouth. Using amoxicillin for fish with this condition can sometimes retard the spread of the bacteria.
The most common sign of red pest on ornamental fish are bloody streaks on the fins, body or tail. The condition can become so severe that the tail or fins actually fall off if not treated with amoxicillin. This is an internal bacterial infection that can be addressed by adding the antibiotic to the fish’s diet. It is rarely seen in healthy aquariums.
Amoxicillin for fish with tuberculosis is not always effective because this disease is hard to cure. It is not the actual tuberculosis that affects humans but is a closely related bacterium that attacks certain fish. This slow-growing condition may cause sores and lead to the loss of scales or a curving of the spine. Infection might spread to humans, especially if a cut or scrape on the hand comes into contact with bacteria in the tank.
Dropsy and scale protrusion can be identified by scales that stick out on the fish’s body. Dropsy might also cause the body to swell, and red sores or streaks might appear. Scale protrusion usually first appears in patches when pustules under the skin affect respiration. As the disease progresses, the fish may lose scales and eventually die. Using amoxicillin for fish with these conditions could be effective if used early.
Amoxicillin capsules can be added to a fish tank for five to 10 days. The infected fish should be isolated in a separate tank during treatment so other fish are not exposed to the bacteria. Tanks also should be sterilized after using amoxicillin for fish that show signs of bacterial disease.