Fin rot

Fin rot is a bacterial disease that can occur in any ornamental fish aquarium. Especially fish with a weak immune system suffer from the infection.

Definition of fin rot and symptoms

Fin rot occurs mainly in guppies, fighting fish, discus fish and goldfish. White areas become visible on the fins of the fish. The highly painful disease spreads from the tip of the fins towards the base of the fins. The base of the fins is red and inflamed. The whitish areas are fraying more and more. Holes form in the fins. Swimming movements seem hectic and restless. Finally the fins fall off completely. The bacterial inflammation infects the body. The fish rub against objects in the aquarium or sit in a corner. They make an apathetic impression and do not eat.

Summary of the main symptoms

  • The fins are frayed, faded and holey
  • The fish rub against objects
  • The fish sit on the bottom of the aquarium
  • little food is consumed


Mouth and fin rot is caused by bacteria, pseudomonads and aeromonads. If the fish’s immune system is weakened by overstocking, stress, poor-quality food or lack of hygiene, these bacteria multiply strongly and cause inflammation. The inflamed tissue of the fins dies. Fin rot can occur together with other diseases such as fish tuberculosis or fungal infection.


If the fin rot is acute, the inflammatory processes spread rapidly. The fish die within a few days.

If the fin rot is chronic, most fish can be cured by using medication. The tissue regenerates quickly. If the fins have already fallen off completely and the fin base is damaged, healing is no longer possible. After the fin base has died and the fish body is infested with bacteria, the fins cannot grow back.

Fin rot is a factor disease. It is not transmissible from fish to fish and there is no infection.


The earlier a treatment is carried out, the greater the chances of recovery. All fish in the aquarium must always be treated, even if they do not yet show any symptoms of disease.

Secretion of sick fish

Fish should be placed in a quarantine tank at the onset of symptoms to protect them from attack by other fish. Secretion facilitates therapy with medication.

Reduction of stress factors

  • Improvement of water hygiene
  • no overstocking
  • high-quality lining
  • optimal water temperature
  • reduce too high nitrite levels in the water
  • Increase oxygen content of the water


The use of drugs helps to reduce the bacterial pathogens. Final success can only be achieved by changing the husbandry conditions at the same time.
Liquid medicines such as JBL Ektol Fluid or eSHa 2000 not only kill the germs. They promote healing of the affected areas and reduce stress. The additional administration of vitamin preparations supports the immune system.

After treatment with medication, the aquarium filters must be replaced or cleaned with activated carbon. Depending on the manufacturer, a water exchange may be necessary.

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