This disease appeared relatively recently in Japan. It appeared only on the red pattern and looked as though this was being eaten by some parasite. The affected area was raised and discolored with a whitish orange cast. There has been no treatment found yet, except to remove it surgically, but a scar will stay. If this disease occurs in a show quality Koi, the fish will lose its value because of the scar on the red pattern.

Some Koi keepers in Japan think that Hi Eating Worm disease is caused by overfeeding Spirulina (algae that is added to the Koi food and improves the red color), and also feeding aged oxidized high protein food.

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