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Koi has ~5 Qty, 1/4" white bumps on body


LawnSite Gold Member
Central Jersey
Well I have three Koi in our pond and I was cleaning it this week. I pulled the fish out and placed in a seperate container. I then noticed that one of the Koi has about 5 of these white 'bumps' that are about 1/4" round all over his body. I tried looking it up in some books that I have but no luck.

Any idea what this is? Is it fatal, unhealthy? Sign of something wrong in the pond? Test indicates nitrites and nitrates are at safe levels.

Think I should quarantine him from the other two?
Caused by Ichthyopthirius multifiliis. The white spots on the skin, gills and fins are individual protozoan cells that are under the skin and feed on the body fluids and cells. They then punch out of the skin and fall to the bottom of the pond, collect together and begin breeding, the offspring then re-invest the fish.

As well as white spots symptoms are scratching and swimming into the water inlet, failure to feed and lethargy. It is fatal if untreated. Fortunately commercial white spot remedies are widely available.

Available remedies:

Paracide Green
Weco Nox-Ich