Goldfish Chilodonella


Chilodonella is a parasitic goldfish illnesses. A severe debilitating condition, the parasite can lie dormant for long periods of time until poor water quality or stress to the goldfish causes rapid reproduction of the chilodonella.

Discovery of chilodonella in the early stages is difficult due to the small size of the parasite. This makes it very hard to spot.


Like many goldfish illnesses, some of the signs of infection are behavioral:

  • Clamped fins
  • Rubbing
  • Gasping at the surface
  • Labored breathing
  • Loss of appetite
  • Lethargy
  • If the gills are affected, an increase in breathing rate
  • A light-blue opaque layer on the skin between the head and dorsal fin
  • In the later stages of infection the skin becomes swollen

Chilodonella is a major threat to goldfish. If it affects the gill area, the goldfish will usually die, or at least suffer long term damage. It is very important to start treatment immediately goldfish illnesses like this are discovered.

How to treat Chilodonella?

Luckily, chilodonella is easy to treat and one treatment is usually sufficient.

Usual treatments are:

  • Potassium Permanganate
  • Malachite and formalin
  • Copper baths
  • Salt baths