Fin Rot

Fin Rot showing on a fighting fish
Fin Rot showing on a fighting fish
A clear example of finrot
A clear example of finrot

Fin Rot is a bacterial disease that most fish can get that is generally caused by poor water quality. It is important for an aquarist to get to the root cause of the issue rather than just treat the symptoms with a medication.


In a nutshell, if your fish has fin rot then you are probably doing something wrong. Common causes of poor water quality can be as follows:

  • Overfeeding
  • Not enough water changes
  • Not changing enough water
  • Not checking water perimiters
  • Doing water changes incorrectly
  • Not cleaning the filter properly
  • Over populated aquarium
  • Keeping nippy specimens with flowy tailed specimens


  1. Recommend doing a 50% water change (you should also maybe bring a glass jar of water for your aquarium shop to test)
  2. Buy one of two medications – fungus treatment (generally makes the water go green) or melafix (clear in the water)
  3. Repeat dose of melafix treatment daily / fungus treatment is a one off dose that lasts 5 days
  4. After 5 days, do another 50% water change and then repeat treatment
  5. Aquarium Salt is another way people sometimes treat fin rot, I’d rather you spoke to us about it first as you need a strong dose to be successful this way.


  1. Do NOT overfeed your fish – most fish are better fed twice daily with all of what you give them consumed within 30-40 seconds
  2. Water Changes – if you are not vacuuming your tank with a gravel vacuum then you should call us and we can show you the process of cleaning an aquarium. Also ensure you do water changes regularly enough as to keep nitrates in check. Most importantly ensure you are changing enough water to satisfy water parameters compared to what you are feeding your fish !!
  3. Check your P.H. weekly, and/or after water changes. Goldfish ideally should be at 7.5 or so, most tropicals 7.0, African cichlids 7.8-8.4, discus & tetras 6.0-7.0, American cichlids 6.6-7.5.
  4. Research your fish and their tank mates for compatibility issues.
  5. Do not over populate an aquarium.