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wikiHow to Treat Fin Rot

Three Parts:Cleaning Your Fish’s TankApplying Medication and Herbal TreatmentsPreventing Fin RotCommunity Q&A

Fin rot is a common symptom of a fungal disease that can affect a variety of fish, from Betta fish to goldfish. It is often caused by a dirty tank, poor care, or exposure to other fish who have infectious diseases. Your infected fish may have fins that appear to be torn and ragged, as if they are rotting away. The fin rot may also cause your fish to become discolored and lethargic.[1] If fin rot is not treated properly, it can lead to permanent damage on your fish’s fins and be fatal for your fish. Fin rot is also highly contagious and should be contained as soon as possible so it does to affect the other fish in your tank.

Part 1
Cleaning Your Fish’s Tank

  1. 1
    Take the affected fish out of the tank. Start by removing the affected fish from the tank and placing him in a separate tank with clean, fresh unchlorinated water.[2][3]
    • You will also need to remove the other fish in the tank to a separate container with clean, fresh unchlorinated water. Use a different net to remove the other fish as fish rot can be spread through shared nets. Do not place the affected fish in the same container as the other fish as this can cause the fin rot to spread.
  2. 2
    Wash the tank and all the tank accessories. You will then need to drain the tank of all the water in the sink. Take out all the tank accessories as well as the gravel in the tank.[4][5]
    • Give the tank a good wash with hot water. Do not use soap when you clean the tank. Use paper towels to get into the crevices of the tank and make sure it has been cleaned thoroughly.
    • Soak the tank accessories in hot water for five to ten minutes. If you have live plants, soak them in lukewarm water. You can then take them out of the water and let them air dry.
    • Wash the gravel with warm water and hoover it with a small vacuum to get rid of any dirt or debris.
  3. 3
    Do a 100% water change. Once you have washed the tank thoroughly and let it air dry, you can place the gravel and the tank accessories back into the tank. If your tank is uncycled, do a 100% water change using dechlorinated or conditioned water. Make sure the water is at 80-82 degrees F (26-27 degrees C).[6]
    • If your tank is cycled, meaning there is a water filter and an air pump, you can do a 50% water change.[7]
    • If your tank has a water filter, you should take a bucket of the fresh tank water and wash the filter with the water. Once the filter is cleaned of any gunk or dirt, you can place it in the tank. Do not use tap water to clean the filter as this can contaminate the filter.
  4. 4
    Check the pH of the tank water. Before you put your fish back in the tank, you should use a pH test kit to ensure the water quality is good. The pH should be around 7-8 and the ammonia, zero nitrites and nitrates should be no higher than 40 ppm.[8]
    • Once you have confirmed the water is suitable for your fish, you can slowly add the fish back into the tank, including the fish with fin rot. You may then add antibiotics or antifungal medication to the tank water to help kill the fin rot. The combination of a clean tank and medication should help your fish to get rid of the fin rot.

Part 2
Applying Medication and Herbal Treatments

  1. 1
    Use antibacterial fin rot treatment. If your fish’s fin rot does not improve within a few days of cleaning and treating the tank, you may want to try antibacterial fin rot treatment. You can find this medication over the counter at your local pet store. Look for fin rot medication that is made for your type of fish, such as fin rot medication for a Betta fish or a goldfish. Follow the dosage directions on the label.[9][10]
    • These medications often contain antibiotics to kill off the fungal infection, such as erythromycin, minocycline, trimethoprim and sulfadimidine. Make sure the fin rot treatment does not contain any organic dyes, as they can be toxic to certain fish.
    • Popular types of fin rot treatment include Jungle Fungus Eliminator and Tetracycline. You can also use brands like Maracyn, Maracyn II, Waterlife- Myxazin, and MelaFix.[11]
  2. 2
    Try tea tree oil and salt. An alternative to commercial medication is the use of tea tree oil and salt. However, tea tree oil is not considered a reliable treatment and should be used as a preventative measure rather than a cure. You may need to supplement the tea tree oil treatment with antibacterial medication or antibiotics.[12]
    • You can add a one to two drops of tea tree oil to the tank water to keep the water clean and sterile. Make sure your fish do not react negatively to the tea tree oil before you add more to the tank the following day.
    • Tonic salt, or sodium chloride, can also be used to prevent fin rot. Add 1 ounce salt per gallon of tank water. Only use tonic salt on salt-tolerant freshwater fish.
  3. 3
    Use an air pump or an airstone when you put medication into the tank. When you treat your sick fish with medication, you should supply extra oxygen so your fish can breath. Medications tend to leech oxygen from the tank water so you will need to give your fish some supplemental oxygen to keep him healthy. Set up an air pump, an airstone, or aquarium housing in your tank to inject more oxygen into the water.[13]
    • If your fish is a Betta, set the air pump on low so the current is not too high, as a high current can be stressful for Betta fish.
    • You should only use the medication for the duration of time specified on the label. Medication can be stressful for fish and should only be used on a by need basis.

Part 3
Preventing Fin Rot

  1. 1
    Keep the tank clean and change the water once a week. A clean tank will ensure your fish recovers properly from fin rot and prevent the development of fin rot in the future. Get into the habit of cleaning the tank regularly.[14]
    • If you have a one gallon tank, you should change the water every three days. A 2.5 gallon tank should be changed every four to five days and a 5 gallon tank should be changed every seven days.[15]
    • If your tank is uncycled, you should do a 100% water change every time you clean the tank. Wash all the tank accessories and the gravel as well.
    • Add aquarium salt to the water after every cleaning to keep the tank water healthy and monitor the pH of the tank so it is comfortable for your fish.
  2. 2
    Make sure the tank is not overcrowded. Though it may be tempting to fill your tank with lots of fish, overcrowding can lead to high stress levels and a higher risk of disease for your fish. Make sure your fish are compatible with each other and have more than enough room to swim around and interact in a healthy way.[16]
    • If you start to notice that certain fish are nipping or biting at each other, this may be a sign that your tank is overcrowded. You may need to remove several fish from the tank or isolate one fish who seems to be acting aggressive towards the other fish.
    • Certain fish are known to be fin nippers, including tiger barbs, serpae tetras, and black widow tetras. Angelfish and catfish can be fin nippers as well as pufferfish and targetfish. If you have any of these fish in your tank, keep an eye on them and separate them from other more vulnerable fish, like guppies.[17]
  3. 3
    Give your fish high quality food. Try to give your fish a varied diet of high quality food and stick to a consistent feeding schedule. Overfeeding and underfeeding your fish can lead to a poor immune system and put your fish at a higher risk of diseases.[18]
    • Giving your fish too much food can also introduce too much bacteria into the tank, as uneaten food will float around in the water and increase the concentration of bacteria in the tank.

Community Q&A

Add New Question
  • What medications can I use for fin rot on betta fish?
    wikiHow Contributor
    Betta Revive is one such medication, effective for various diseases including fin rot.
  • My fish fins have tearing in them and I don't know the reason. Is it a disease?
    wikiHow Contributor
    Are there any sharp ornaments or plants in your tank? If so, that could be the cause of the fins tearing on your fish. Take out any sharp objects from your tank and watch your fish carefully. Usually, the fins will grow back when your fish becomes less stressed.
  • Does the fin repair itself?
    wikiHow Contributor
    With a clean and roomy environment, good high protein diet, correct pH and temperature and, if necessary, medication will have your fish on the road to recovery quickly.
  • What are the names of the medicine for fin rot?
    wikiHow Contributor
    There are three ways to treat fin rot: anti-bacterial treatment, antibiotics, and fixing the environment. Fixing the environment is the most important element, because if the tank is in a bad way the fish will become reinfected with fin rot in the future. Do a couple of large, 20-50% water changes with clean, aged water, and try to suck up as much debris and detritus as you can. Check and clean all your filters, and give the gravel a good clean as well, especially if you’re using an undergravel filter. Look out for any tank bullies that are nipping or fighting
  • Can goldfish suffer from fin rot?
    wikiHow Contributor
    Yes, any fish can suffer from fin rot. Treatment options are generally the same between species since it's caused by the same issue: bacterial growth in a tank that has been contaminated/hasn't been cleaned often enough.
  • My dad bought two goldfish and he has them in a tank together. He has noticed that they do not look well and are lying at the bottom of the tank cuddled up to each other. The only time they move is when we feed them. Can you tell me why they are acting this way?
    wikiHow Contributor
    Your fish may not be getting enough oxygen in their tank. You may need to do a water change and make sure you change the water every three to five days. You may want to clean the tank before you add in fresh, conditioned water. Another option is to buy an air pump and put it in the tank so the goldfish get enough oxygen in the water.
  • How can I tell if my fish is recovering?
    wikiHow Contributor
    See if your fish's personality and activity improves over a few days. Take mental notes of where the tears are so you can notice when they are getting better.
  • Can I treat the entire tank for one fish?
    wikiHow Contributor
    Because you should change the water more frequently when treating a fish with fin rot, it would be better to isolate the affected fish in a smaller quarantine tank to ensure you're giving it the cleanest environment to recover in. Some treatments for fin rot can stress a healthy fish, so it's better to nurse the affected fish back to health before returning it to the larger tank.
  • How often can you use aquarium salt in your tank in between water changes? Can you use Bettafix with it?
    wikiHow Contributor
    You can add aquarium salt every time you change the water. You can use Bettafix instead of aquarium salt, but do not add both at the same time. Some Betta fish owners recommend using aquarium salt instead of Bettafix as Bettafix can be dangerous for your fish.
  • What does keep fin rot at bay?
    wikiHow Contributor
    Regular water changes, minimal stress, and a properly filtered tank. It may take awhile for the fin to grow back, but it is possible. I had a guppy who had its tail eaten off by another fish. After removing the aggressor into a different tank, it took 6-8weeks and the guppy had its tail completely mended.
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In other languages:

Español: tratar la putrefacción de aleta, Italiano: Trattare la Corrosione delle Pinne dei Pesci, Português: Tratar o Apodrecimento de Barbatanas, Русский: лечить плавниковую гниль, Deutsch: Flossenfäule behandeln, Français: traiter la pourriture des nageoires

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