How to Treat Fin Rot

Fin rot is a common symptom of a bacterial 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]XResearch source} 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

Part 1 of 3:

Cleaning Your Fish's Tank

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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]XResearch source}^{[3]XResearch source}
- 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
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]XResearch source}^{[5]XResearch source}
- Give the tank a good scrub with hot water.^{[6]XExpert SourceCraig Morton
  Aquarium Specialist, Aquarium Doctor Inc.Expert Interview. 21 July 2020.} 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 too.^{[7]XExpert SourceCraig Morton
  Aquarium Specialist, Aquarium Doctor Inc.Expert Interview. 21 July 2020.} Use warm water and hoover it with a small vacuum to get rid of any dirt or debris.
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3
Do a 100% water change.^{[8]XExpert SourceCraig Morton
Aquarium Specialist, Aquarium Doctor Inc.Expert Interview. 21 July 2020.} 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).^{[9]XResearch source}
- If your tank is cycled, meaning there is an established colony of beneficial bacteria built up on the submerged surfaces of the tank (accumulated mainly through fish living in the tank and excreting nitrogen), you can do a 50% water change; subsequent smaller proportion water changes are recommended.^{[10]XResearch source}
- If your tank has a water filter, you should clean that as well.^{[11]XExpert SourceCraig Morton
  Aquarium Specialist, Aquarium Doctor Inc.Expert Interview. 21 July 2020.} 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
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.^{[12]XResearch source}
- 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.

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Applying Medication and Herbal Treatments

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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.^{[13]XResearch source}^{[14]XResearch source}
- 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.^{[15]XResearch source} API Bettafix is another option.^{[16]XExpert SourceCraig Morton
  Aquarium Specialist, Aquarium Doctor Inc.Expert Interview. 21 July 2020.}
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.^{[17]XResearch source}
- 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
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.^{[18]XResearch source}
- 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

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Preventing Fin Rot

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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.^{[19]XResearch source}
- 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.^{[20]XResearch source}
- 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
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.^{[21]XResearch source}
- 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.^{[22]XResearch source}
- In general, don't have more than 1 inch (2.5 cm) of fish per 2 gallons (7.6 L) of tank space.^{[23]XExpert SourceCraig Morton
  Aquarium Specialist, Aquarium Doctor Inc.Expert Interview. 21 July 2020.}
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.^{[24]XResearch source}
- 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.

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What's the best way to clean a fish tank?
Craig Morton
Aquarium Specialist, Aquarium Doctor Inc.
Craig Morton is the CEO of Aquarium Doctor Inc. based in Huntington Beach California and servicing Orange County, Los Angeles County, and the Inland Empire. With over 30 years of aquarium experience, Craig specializes in creating custom aquarium designs along with aquarium installation, service, and maintenance.
Craig Morton
Aquarium Specialist, Aquarium Doctor Inc.
Expert Answer
You want to scrub the glass, clean all of the gravel, do a water change, and clean any filter media you have.
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How can I tell if my betta fish is sick?
Craig Morton
Aquarium Specialist, Aquarium Doctor Inc.
Craig Morton is the CEO of Aquarium Doctor Inc. based in Huntington Beach California and servicing Orange County, Los Angeles County, and the Inland Empire. With over 30 years of aquarium experience, Craig specializes in creating custom aquarium designs along with aquarium installation, service, and maintenance.
Craig Morton
Aquarium Specialist, Aquarium Doctor Inc.
Expert Answer
Check your betta for cloudy eyes, white film on its skin, and torn fins. These can all be signs that something is wrong.
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Can you treat fin rot with salt?
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This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.
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In some cases you can treat fin rot with salt but this remedy should only be used on salt-tolerant freshwater fish. You can use tonic salt, or sodium chloride, adding 1 ounce (28g) of salt per gallon (3.7 liters) of tank water. Some fish owners advise using it only when the fin rot is particularly aggressive. You can also add aquarium salt to the water after cleaning the tank (check it’s suitable for freshwater fish), so the water is healthy––this can be done after each cleaning.
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API Melafix and pimafix added together to the tank works wonders, but you have to keep up with constant water changes. Make sure to remove activated carbon from the filter to get the full affect of the medicine.
Never use Beta fix. Always use Primafix for fin rot. A lot of people think fin rot is a bacteria but it’s really a fungus.
Do not overcrowd your aquarium, keep your tank clean, and don’t over feed your fish to help prevent fin rot.
Change 25-50% of the water daily.

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