Last Updated on April 24, 2023 by Coral Realm

Fin and tail rot is quite simply the deterioration of the fins or tail, this is usually a symptom caused by another disease – however it has been known to occur by itself. This disease is common within community tanks that house a variety of different species. Fin rot treatment and prevention can be quite simple however.


Fin and Tail Rot Causes:

Fin and tail rot is caused by a bacterial infection where the body’s immune system weakens whilst trying to fight an illness. This usually occurs from stress within the fish tank, this can be from various factors such as overcrowding, aggressive tank mates, incorrect husbandry (temperature, lack of cleaning) or general neglect. Not cleaning the aquarium filter can be a cause as debris can get clogged and reduce filtration power, and will also get to decompose and release harmful compounds into the water column.


It is usually clear when a fish is suffering from fin and tail rot, so if you suspect your fish has this disease, check them over for the following symptoms:

  • Deterioration of the fins or tail, with frayed edges
  • A fade in their color
  • Gaps in their fins or tail
  • Some may experience inflammation at the base of the fin

Prevention and Fin Rot Treatment:

Prevention and Fin Rot Treatment

Preventing fin and tail rot

To prevent fin and tail rot, you need make sure your fish are in the correct environment. This includes having the correct temperature for the species, ensuring they are housed with other compatible species, having a large enough tank and carrying out cleaning procedures when needed – this includes a water change of 25%, removing any debris and completing water tests.

To ensure you have and maintain the correct temperature for your freshwater fish or saltwater fish you should have an aquarium heater installed, with an aquarium thermometer opposite to check the temperature. You can easily remove debris using an aquarium vacuum cleaner.

Water tests are essential for checking for pH, chlorine, nitrite, ammonia and nitrate levels, these can be purchased in either a stick or chemical form:

Aquarium test strips  

API 5 in 1 Aquarium Test Strips
  • Contains one (1) API 5-IN-1 TEST STRIPS Freshwater and Saltwater Aquarium Test Strips 4-Count Box
  • Monitors levels of pH, nitrite, nitrate carbonate and general water hardness in freshwater and saltwater aquariums
  • Dip test strips into aquarium water and check colors for fast and accurate results
  • Helps prevent invisible water problems that can be harmful to fish and cause fish loss
  • Use for weekly monitoring and when water or fish problems appear

These water test strips are a quick and easy alternative to the master test chemical kits, complete with four strips and a chemical chart. One of these strips is to be placed into the water for a short amount of time and the colors on the strip should then be compared to the color chart – this will then accurately tell you the levels of PH, nitrite, nitrate, carbonate and general water hardness.

Master test kit

API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit, White, Single, Multi-colored
  • Contains one (1) API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit, including 7 bottles of testing solutions, 1 color card and 4 tubes with cap
  • Helps monitor water quality and prevent invisible water problems that can be harmful to fish and cause fish loss
  • Accurately monitors 5 most vital water parameters levels in freshwater aquariums: pH, high range pH, ammonia, nitrite, nitrate
  • Designed for use in freshwater aquariums only
  • Use for weekly monitoring and when water or fish problems appear

This master kit is a more advanced alternative to the testing strips, with 7 bottles of testing solutions, 1 color card and 4 glass tubes. This kit will measure the pH, high range pH, ammonia, nitrite and nitrate, this kit may give you a more accurate result, however there is more of a risk of disrupting the process by putting too many or too little drops in the test tubes. 

Fin rot treatments and tail rot treatments are fairly simple – firstly, if not all of the fish are suffering, the affected fish should ideally be placed into a separate tank to be treated and to avoid the disease from spreading to the other fish.

However, if the disease is being treated with the correct supplies this isn’t compulsory. Water treatments aimed at fin and tail rot should be used to tackle the disease, and the fish should then be closely monitored until they start to heal, if the cause is bullying within the tank, then the fish should be separated and placed with compatible tank mates; the most effective and affordable treatments for fin and tail rot are listed below:

Fin Rot Treatments

API Furan-2

This powder medication treats a variety of bacterial infections, complete with 10 packets filled with pre measured medication, this treatment is simple, effective and easy to use. You should remove the filter media before using this treatment for fin rot as the media can absorb it.

For each 10 gallons of water in your tank you will need one packet of this medication. Wait 24 hours and dose the tank again. After another 24 hours undertake a 25% water change. Then repeat this process again so you have dosed the aquarium four times in total with API Furan-2, then undergo a final 25% water change. Finally add new filter media and activated carbon, as the water may be discolored due to the medication.

As this is an antibiotic treatment with Nitrofurazone as the active ingredient, it doesn’t discriminate against good and bad bacteria n your tank. As such the helpful bacteria in your substrate may be killed as well. You can add API Quick Start Nitrifying Bacteria to help reintroduce beneficial bacteria quickly.

API Melafix

Melafix Liquid Remedy 16 oz.
Made with Tea Tree Extract API Melafix is safe to use with even the most delicate of fish species, and will not harm or affect your biological filter media.

This formula is very similar to the API Furan-2, however it is formulated with ingredients that target the regrowth of fins and tails, this may be a more suitable option to specifically treat fin and tail rot.

You should remove any activated carbon from the filter or tank before you use this fin rot treatment as it will be absorbed by the carbon and the effectiveness will be greatly reduced.


Preventing fin and tail rot before it affects your fish is always the best policy. Make sure you keep your fish tank nice and clean; have a filter installed, ideally with chemical, biological, and mechanical media. Also undergo regular water changes, and remove dirt and debris as it builds up.

Test your water regularly to ensure the water chemistry remains in the parameters your fish require. If it isn’t then you can work to rectify this.

If you do find fin and tail rot in your tank you can use the following fin rot treatments; API Furan-2 and API Melafix.

Featured Image Photo Credit: Dizzy Respect (WikiCommons)

About the author

Coral Realm

Leave a Comment