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Fin Rot in Clownfish

Fin Rot

Fin Rot in Clownfish

Fin Rot in Clownfish

Fin Rot (also known as Tail Rot) is one of the most common preventable bacterial diseases that occurs with aquarium and pond fish.

Fin rot can be the result of either a bacterial infection (Pseudomonas fluorescens) which causes ragged fin rotting, or a fungal infection that produces a white edge and rots the fin more evenly.


Fin Rot starts around the edges of the fin or tail and untreated, progressively deteriorates the tissue until it reaches the base of the fin or tail.  The fins become frayed and often look like they are rotting off the fish.  The colors usually fade or look washed out.

If you believe your fish is suffering from fin rot, look for the following symptoms:

  • The fins and/or tail have frayed edges
  • The edges of the fins or tail have turned white and in some cases, brown or black.
  • Parts of the fin or tail have rotted or dropped off the fish.
  • Inflammation is visible at the base of the fins.
  • Loss of appetite, inactivity, lethargic.


Fin rot is most often caused by a dirty tank and poor water quality which is the result of poor maintenance.   Fin rot can also be caused by injuries such as mishandling of fish,  fin nipping and bullying by other tank mates, or contamination by other fish introduced into the tank who may have the disease.


  • Clean the gravel at the bottom of the aquarium to remove as much waste as possible.
  • Perform a 25% water change of the total volume of your tank.
  • Test the tank water for ammonia, nitrates, nitrites, pH, and temperature.   All in one test strips are readily available for home testing.
  • Move affected fish to a quarantine tank unless all of the fish are affected.  Disinfect the net to prevent the spread of the fin rot.
  • In the case of bullying or fin nipping; remove the bullied fish to prevent the disease.
  • Treat the affected fish with *Melafix, **Pimafix, API Fin & Body Cure, API E.M. Erythromycin, Tri-Sulfa Tablets, Fish Mox Forte Amoxicillan , KanaPlex, and Methylene Blue.   Remove active carbon from filters during treatment.

(When treatment is successful, damaged fins and tail will slowly grow back after a few weeks.)


  • Maintain a clean aquarium environment by performing regular water changes and testing to prevent bacteria buildup that can lead to fin rot.
  • Don’t overcrowd your tank.  Fish waste builds up quickly even with the best of filtration systems.
  • Don’t overfeed your fish.  Small quantities of quality foods fed two or three times daily is preferable to a single feeding and minimizes waste buildup.   Your fish should consume whatever you feed them within 5 minutes and any uneaten food should be removed from the tank.
  • Only keep compatible species in a community tank environment.  Watch new additions for bullying or fin nipping and separate them when necessary.   Watch for changes to their fins, tails, body, appetite, and behavior.
  • Quarantine new fish before placing them in a community tank.  It is easier to spot and treat fish diseases in a quarantine tank than in a community environment.

*Melafix is a natural wide range antibiotic formulated to heal a wide variety of mild gram positive bacterial infections like tail and fin rot, eye cloud, mouth fungus and more.  **Pimafix quickly treats fungal and bacterial infections such as cottony growth, fin and tail rot, etc.

Posted in Bacterial Infections, Tropical Fish Diseases, Tropical Fish KeepingComments (1)

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