As with any infection, it's very important to catch it early in order to treat it effectively.


This is where regular, careful observation of your fish and his/her tank conditions can save your fish's life!


In the picture at left, I had noticed a very small spot on my fish. Wanting to see what was going on, I got out the camera and took a picture to get a closer look.


Do you see the problem?

The slimy/fuzzy, 3-dimensional white-ish/grey-ish area can be a classic presentation of a bacterial infection. While this spot is miniscule in the picture, it is important to be aware of such occurrences and monitor them for worsening.


While I was able to see this spot with my naked eye, I was certainly not able to examine it closely without the harsh lighting of the flash, the extreme magnification of the camera and the freeze-frame that a picture offers of an otherwise active fish.


When dealing with such small animals, cameras can be invaluable diagnostic tools, both for examining the animal yourself and for sharing your findings with others.


  • Lesions
    • White/grey color
    • "Cottony"/fuzzy/slimy appearance
    • Somewhat 3-dimensional
  • Possible redness/bloodiness around lesion
  • Possible discoloration/darkening/necrotic tissue around lesion
  • Fins/tissue may be degrading/being "eaten" away if infection is worsening


See photographs above, and of fish on our EXOPTHALMIA ("POPEYE") page

  • Red/bloody streaks visible on skin/body
  • Redness at base of fins
  • Lethargy
  • Refusal to eat


  • Check all parameters (at the very least, temperature, ammonia (and nitrite/trate in a cycled tank))
  • If any parameters have drifted out of their ideal ranges, take steps to correct them

In order for your fish to recover from any illness, you must make sure that they are not experiencing any environmental stress - they must be provided with a clean and healthy environment in which to heal and to prevent future infection.

  • If minor and uncomplicated (like the small patch in the picture above), maintain pristine water conditions and observe fish.
    • If infection worsens, reassess and choose an appropriate antibiotic (see below)
  • If the infection is moderate to severe, or is worsening, you will need to medicate the fish.