Chilodonella infections in pond fish

In the spring you may notice one or several fish do not look well.  They are lying on their side and are very lethargic.   This usually occurs when the water temperature is between 40 to 50 degrees Fahrenheit.

One common cause is due to a microscopic protozoan parasite known as Chilodonella.

Chilodonella infections are not affected by changes of water temperature, so there is no need to heat the water or move the fish but it is necessary to treat the water and fish to rid the parasite.

What are the symptoms? 

  • Fins will be clamped or folded.
  • Fish will act itchy or they will be flashing.
  • Fish will be lethargic and lean over on their sides at the bottom of the pond but will quickly turn upright and move quickly when startled.
  • Labored breathing is often observed.
  • Excessive mucous production is typically seen (body will look cloudy).

If you observe this behavior–then it is possible that your fish is infected with Chilodonella parasite.

Chilodonella attaches to the skin, gills or fins and will puncture the fish making way for bacterial infections.  These bacteria are Aeromonas hydrophilla and Psudomonas, which grow very fast when water temperature is between 42 and 62 degrees Fahrenheit.  Bacteria will enter puncture wounds in the fish causing infections (ulcers, fin rot) which can be difficult to treat.

How can this be prevented?  Keep it clean!  Often parasites find their way into your pond by mother nature.  We can also introduce risk by adding “new” untreated plants and fish or when wild birds use your waterfall as a bird bath.

To keep your pond parasite free, you need to keep your water clean.  Use very good mechanical filtration, perform periodic filter maintenance and weekly water changes.  Treat the water, periodically with products designed to kill parasites.

If maintenance is not performed, eventually you will need to clean the pond and use products to clear your water and destroy parasites.

Keep your fish healthy during feeding season! Use high quality, vitamin rich koi food.  Read the label!  All koi foods are not created equally!

What is the right treatment? There are several treatment options on the market.

Some treatment options are CystalClear KnockOut PlusMicrobe-Lift Defend, Microbe-Lift ParazoryneSeachem Pond Health Guard, ABI Ultra Clear Potassium Permanganate Solution.

Remember NO treatments are risk-free! 

We have personally used and stock all of these products (and others) and will be happy to assist you with selecting the product that is best for you to use.