Betta Fin Rot – Detection, Prevention, and Treatment

Owning a betta fish can be very enjoyable and as a pet owner, that being said, we want to help you keep your pet healthy. Knowing that betta fish are sensitive to diseases, we will go over everything you must know about betta fin rot and how to treat it. 

Definition of fin rot

Fin rot is a common disease that attacks many fish, with betta fish and goldfish ranking neck-and-neck as the two types of fish that suffer from fin rot the most. It’s a bacterial or fungal disease that infects the edges of the fins, and if left untreated, can cause more drastic developments. This disease has nothing to do with fin biting or nipping. Those are just physical injuries that can happen during a fight with other fish. 

Reasons and causes behind fin rot 

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The main reasons behind fin rot are poor care and water quality. 

Pet store danger

Local pet stores usually keep and sell betta fish in a glass cup or a small vase. This doesn’t allow enough room for them to move around freely. This small amount of water isn’t recycled or properly filtered. Additionally, the water doesn’t have the required temperature or pH. So, it wouldn’t be a surprise if you purchase a betta fish that already suffers from fin rot. 

Aquarium conditions

If you’re able to buy a healthy betta fish that doesn’t have fin rot, it can still catch the disease due to the aquarium conditions. For bettas to be healthy and safe, they must be kept in a large tank with perfectly clear water that has a temperature of 78°F – 80°F (25.6°C – 26.7°C). By ensuring the proper environment for your fish, you can keep the bacteria from breeding in your tank.


Fin rot is a bacterial disease that usually arise from improper care of an aquarium. The bacteria attacks the outer membrane of the fins and start to eat them. Eventually the damaged internal tissues are left exposed to any other upcoming threats. These bacteria can only infect their fins when their immune system is weakened.

The difference between bacterial and fungal fin rot

In general, both forms of diseases attack the fins, cause damage to the tissues and attack when the immune system is weakened. But, how exactly can you differentiate between bacterial and fungal fin rot? 

Bacterial fin rot is caused by bacteria that attack the fins and causes uneven damage. The rupture in the fins is large at some part and small in other parts. As for fungal fin rot, the damage is equal and even across the fins. 

Fin rot symptoms

Symptoms can differ according to the case or state of the disease. Fin rot can be mild, major or deadly. 

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Mild fin rot symptoms

Mild fin rot is the phase when your betta’s immune system starts to weaken. When noticing these symptoms, you should take immediate action.

  • Fin tip start to look sore and colors start to fade away to brown or white
  • Fin colors gradually become darker
  • Fin edges begin to show signs of slight damage
  • Damage stays on their fins and doesn’t spread to the rest of their bodies

Major fin rot symptoms

Major fin rot is the phase where the betta’s immune system becomes worn out. Your betta is more open for attacks and infections. Fin rot starts to become more serious and controlling the disease becomes harder. 

  • More than a centimeter of their fins are dead 
  • Fins retreat to a point where they’re very close to the body
  • Fins’ color become very dark to the extent that you’ll be able to notice that the fins are starting to die
  • Fins become covered with white clouds, indicating the infiltration of fungi
  • In the end, sore red dots will appear on their fins

Deadly fin rot symptoms

Deadly fin rot is the phase where the infection reaches the fish’s body. The immune system becomes almost dysfunctional. In the end, your betta fish is very likely to die. 

  • Fins are completely destroyed and retreated to the body
  • Infection reaches the body. The body starts to experience most of the same symptoms as their fins, such as discoloration and white clouds
  • Gradually, the body of the fish rots away
  • White clouds on what’s left of the fins

As you can see, betta fish go through a lot before they become utterly helpless. There is still hope to treat and save the fish from this disease until the major symptoms show. There is a chance that your betta can be treated, as long as the infection does not reach the body and the fins are completely destroyed. Treating betta fish that suffer from severe fin rot won’t always be possible, however, the sooner you can treat it, the better.

Treatment and prevention

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Just as the symptoms differ, the treatment process is different for each state. You have to classify the level of danger your Betta fish is facing. Also, you need to choose a treatment process that is appropriate for the ecosystem. 

Mild fin rot treatment

  • Make sure that the water temperature ranges between 78-80°F (25.6-26.7°C), and the pH ranges between 6.5 – 7. To keep track of this, you can use a fish tank thermometer and fish tank pH testing strips.
  • Change half of your aquarium’s water, and make sure that the water is perfectly filtered and chlorine-free. Use a gravel vacuum to eliminate any wastes or food remains. Wash all the aquarium’s accessories using hot water only.
  • Monitor the progress and check for any healing signs. Changing 25% of the water each week and keeping the ideal water parameters will eventually make your betta heal.

Major fin rot treatment

  • Remove your sick betta from the aquarium and isolate it in a hospital tank (separate tank) of 2 gallons capacity. 
  • Make sure that the hospital tank meets all of the required conditions for their survival. The tank must be free of plants, substrate and mates.
  • Change the filter and set up of the aquarium. Wash all the accessories and give the aquarium all the required conditions. 
  • For the hospital tank, place aquarium salt in it. The aquarium salt helps in healing wounds and prevents nitrite uptake. Make sure that the aquarium salt dissolves completely before placing your betta. Any precipitates of the salt could cause severe burns to your fish. 
  • Continue to monitor the weekly progress, as you change about 25% of the aquarium water. 

Deadly fin rot treatment

  • Note: have to use medicine and hope for the best. Here’s an over the counter version of the medicine.
  • Remove the sick betta from the aquarium and isolate them in a hospital tank (separate tank) of at least two gallons
  • Make sure that the hospital tank meets all of the required conditions for their survival. The tank must be free of plants, substrate and mates
  • Insert an air bubbler, to provide the necessary oxygen, in case some of the medication absorbs oxygen from the water
  • Remove everything from the tank and set up the aquarium as if it is brand new
  • After consulting a vet, insert an antibiotic (recommended from prescription) in the hospital tank. Put equal doses of the antibiotic at equal intervals of time. This prevents the rise of antibiotic resistant bacteria. 
  • After your Betta shows some signs of progression, return your Betta fish to its original aquarium

Step by step, as the treatment continues, the fin membrane begins to regrow and regain its original shape, form and colors. However, since it’s a very difficult and delicate process, make sure to keep away any tank mates that can cause danger to the fish. 

To prevent fin rot from occurring in the first place, make sure to monitor your betta and the aquarium thoroughly. Provide them with a safe, healthy ecosystem. Maintain the ideal water parameters. Also, make sure to put them in a wide aquarium, where the water can continually be recycled. 

In the end, we hope that you gathered a great deal of information about the Betta fish and fin rot disease.