The symptoms of fin rot are quite easy to determine, the fins start to shred and the edges turn a brownish colour. Your betta will start to look poorly and small holes will start to appear in the fins.

Fin Rot Explained

Fin Rot is brought on by poor water conditions (neglecting the state of the water in the aquarium) causing bacterial infection.

In order to treat this infection you will need a fungus eliminator which is available in most pet stores. Make sure you keep the aquarium water fresh and clean. Purchase some aquarium salt and add 1 teaspoon to every gallon of water your tank holds. I recommend a tank of 3 gallons. Only add this salt when you are changing the water as the salt does not evaporate and will build up a strong toxic level if added on a daily basis. The water should be changed at least once a week or more if it starts to get cloudy earlier. Aquarium salt aids in the betta’s breathing and initiates better recovery processes.


Picture shows healthy betta


Make absolutely certain that when you are applying the fungal eliminator you check your dosage and only use the prescribed amount written on the package, this is normally about a quarter of a teaspoonful for each gallon of water to be added every third day until there is an obvious improvement in your betta’s fins. I have put the normal dosage here, but still check your product paperwork to make sure what the correct dosage for the eliminator you purchase is. This salt can be used in a preventative way in that you can add the dosage prescribed each time you change the water. This will help to keep your bettas healthy.

It this treatment fails, your betta may be suffering from Flexibacter Columnaris, which can and does get mistaken for Fungal Infection. Flexibacter Columnaris, also known as cotton mouth has the added symptom of white spots or paleness on the edges of the scales and fins. It also appears on the mouth. The way you have to treat this is using copper sulphate, antibiotics and chemicals. The common treatments are Acriflavine, Terramycin and Furan, these are supplied by pet stores. Ask which the storekeeper recommends. Filtration removes the medication from the tank very quickly, so if you have filtration in your aquarium and use carbon filters, then stop using filtration whilst the treatment is ongoing.

You should change the water frequently if the bettas are suffering from Flexibacter Columnaris as it is highly contagious. Be sure to clean all your decoration accessories and gravel at the same time. Any nets, vacuums etc. that you use must be disinfected so that the spread of the disease is curbed. This disease can kill and in chronic cases it appears slowly taking days to kill the fish. It has been known to kill entire population in only a short time, sometimes in only a matter of hours. The disease is accelerated by high water temperatures, but the down side is if you lower the temperature, it will only slow down the process, not stop it. You need to be quick getting treatment for this disease for obvious reason.


If you follow these steps, you can reduce the chance of your betta getting fin rot or Flexibacter Columnaris :

– When you purchase new fish, you should quarantine them for at least 2 weeks (disease can be prevalent in pet stores).

– Make sure the tank water is kept fresh and clean

– Make sure the fish are fed on a well balanced diet

– Before using any equipment make sure it is well disinfected in order to stop the chance of spreading bacteria


Using these steps to health you will also reduce stress in your fish. Stress is the largest contributor to disease in all animals including humans.