Affected Koi look as though they have cotton growing on their body. This is a fungus call Legniasis and Achlyasis and it will occur when the pond has too many Koi and/or poor conditioned water.

First, treat the fish by washing it in a 1.5% to 2.5% salt solution. A Methylene Blue or Malachite Green bath is also recommended. Second, reduce the fish population and improve the filtration system in the pond.

*Information on this page is an excerpt from "KOI" by Grant Fujita, available at the AKCA online bookstore.