Epistylis in Koi and Pond Fish Ponds

Epistylis is a relatively uncommon parasite of Koi, goldfish and pond fish. Indeed, it is so uncommon, that I do not have any good graphics of it. What you would see clinically is a tuft of whitish fluff coming out from under a scale, or from some other wound on the Koi, goldfish and pond fish. It gives the impression of a fungal infection but looks radically different under the microscope. Usually, fish with Epistylis are rather hale, considering they are parasitized. Epistylis does not occur in tanks or environments which are clean, and which have a low organic load. You would normally expect to find Epistylis in unfiltered ponds and lakes on common pond fish. I have not recovered Epistylis from any of the finer, aquarium raised Koi, goldfish and pond fish. I have cleared the few cases I have seen in ponds with massive water changes, removal of the organic load in the system, and the application of 0.3% saline.

The organism is clinically relevant because many people treat these cases as if they were funguses; eventually killing the fish with useless treatments and arriving at the conclusion that fungus is hard to cure. Indeed, they were treating Epistylis with anti fungal remedies and not addressing the true cause of the Epistylis infection = Filth!

The condition of Epistylis is prevalent, but not very common in the typically cleaner environments encountered with Koi, goldfish and pond fish keepers.

Epistylis in Koi and Pond Fish Ponds

control of epistylis

Dr Erik Johnson is a Marietta, Georgia Veterinarian with a practice in small animal medicine. He graduated from University of Georgia with his Doctorate in 1991. Dr Johnson is the author of several texts on Koi and Pond Fish Health and Disease as well as numerous articles on dog and cat health topics.