The following comes from DrJohnson.com about cross contamination of Koi via Goldfish. It was a case in the Ask The Doc section of the site.
I got your address from my friend Jason who you recently helped with a pecan nut problem.
I may or may not have a KHV problem. If I can give you the story I hope you can tell me if there is anything I should do.
I dug a pond last fall and have 2, 5 inch koi doing fine in it. I have 5, 4 inch koi inside doing very well.
I have a lotus in a whiskey barrel that I've had for sometime and put cheap goldfish in for mosquitoes. They usually die quickly and I never thought much about it until I started reading about KHV and saw pics of Koi with KHV. I remember one of the gold fish having a dark patch on its gill cover that looked like a post mortem shot of a koi with KHV.
I have wintered umbrella palms in the lotus barrel.
So my questions.
1. Should I be concerned
2. Is there a nucleic acid test that can test water
3. Is there a non-invasive nucleic acid test for fish
4. At what point should I bring the outdoor fish to you before I move the indoor fish out.
5. Should I throw out the plants or is it safe to put them in the pond
If there are any products I need to purchase from you, please let me know.
Koi Herpes Virus is not a legitimate liability to goldfish owners.
Testing is a mixed bag – – because if you test and it's positive, you have to (by law) go on record with the Federal Government. It's a "legally reportable" disease so the testing agency has to 'tell on you' and that COULD POTENTIALLY mean that you have to surrender your fish to the Fed and the pond gets drained and closed.
Any Koi that carries KHV in cold water will "break" with it when it's warmed to 70-78 DF
Any Koi that is infected with KHV will 'get over it' when it's warmed to 84 DF.
They're not considered ''cured''. By anyone but me, and also everyone in Israel.
The plants (left without fish for a week or two) will bring no diseases with them to a receiving facility. I can say that with even more certainty if the plants are in the seventies DF when you quarantine them.
So if you think the Koi outdoors are harboring KHV all you have to do is bring one up to 75 degrees and give it a week to break.
And if it doesn't, you're golden, on the KHV issue.
Besides a few recommendations on Amazon.com about heaters and air pumps, I don't officially "sell" anything so you're good there 🙂