As the disease progresses, an increasing amount of the fin will be destroyed. As more of the fin erodes away, the fin may start to resemble a semicircular bite shape. [4] X Research source If fin rot becomes severe, the fin will erode to the point of being only a stump. A hole in the affected fin usually indicates a fungal infection, which sometimes occurs simultaneously with fin rot. [5] X Research source Be aware that you may not be able to detect fin rot until the disease is fairly advanced. [6] X Research source
The affected areas may also have white dots,[8] X Research source which could be indicative of a fungal infection.
Fin rot is a bacterial disease. When the fins become damaged, the bacteria can enter the bloodstream through the damaged area and spread the disease throughout your fish’s body.
These behaviors are not specific to fin rot, but can help confirm the diagnosis if his fin damage is characteristic of this disease.
Other bacteria linked to fin rot are Pseudomonas species and myxobacteria.
Nitrate—what ammonia is broken down to during the nitrogen cycle—can also accumulate in the tank and damage your fish’s fins. Decaying live plants and leftover food can increase ammonia and nitrate levels. [11] X Research source
Water that is too cold, as well as water pH fluctuations, can also be stressful to your fish. [12] X Research source
If you have a burrowing fish, he could easily damage his tail and fin if the bottom of his tank contains gravel instead of sand.
Use a sponge filter in the treatment tank. It is less likely than a chemical filter to filter out medications, and is unlikely to stress your fish (like a strong power filter). [14] X Research source Place an enclosed water heater in the tank to maintain a water temperature that is recommended for your specific type of fish. [15] X Research source An air stone will help keep the tank well oxygenated. [16] X Research source The supplies for your treatment tank are available at your local pet store. Continue to monitor the other fish for signs for fin rot. [17] X Research source Separate and treat them if necessary.
Outside of the United States, you may have to obtain the antibiotics through your veterinarian. It is common to use a combination of antibiotics to treat fin rot, since the disease could be caused by several types of bacteria. Methylene blue is a non-antibiotic treatment that can also be used to treat fin rot.
Your veterinarian will use sterile scissors to remove the damaged tissue. He or she will then treat the clean edge with antiseptic. Your fish may need additional treatment if fin rot has become extensive. [19] X Research source The fin tissue is more likely to grow back with minor cases of fin rot. [20] X Research source
Be mindful that the fin rot may be too severe for treatment.
If need be, change the filter and allow time for bacteria to grow that will help reduce ammonia levels in the tank. [23] X Research source Remove any dead plants to reduce ammonia accumulation. Reduce the stress in your fish’s life by keeping him in his own tank, away from the other aggressive fish. You could also use a water heater and thermometer to keep his tank at the right temperature. Remove sharp objects from your fish’s tank (e. g. gravel, sharp-edged decorations) to prevent further physical damage.
