Simply Koi and More Koi

On Sunday I introduced a new koi into my pond that was bought at the national.
Having been sitting in a vat over the weekend I half expected there may be an issue with different temperatures as my pond is currently at 21C, after floating it in the bag for half an hour it was released into the pond.
Fourty eight hours later most of my koi are flashing a lot, I scraped three fish half expecting to find whitespot, nothing.
The next evening the fish were going down hill, flashing, head down, claped fins etc and I was tempted to add MG&F without further evidence.
I decided to have one more scrape and was not surprized to find whitespot, only a couple of immature individuals but that confirmed my suspicions.
My second dose of MF&G will go in tonight and all the koi are showing the effects of the whitespot, bar one, the new koi has no symptoms of whitespot whatsoever and is swimming around as happy as larry feeding as normal.
So my query is, is this normal?

Dave,

No it isn't normal that infected fish are sold at any koi show. If you PM me the name of the dealer I'll investigate to see what I can find.

The new fish shows no sign of infection is it just coincidence that I have an outbreak or is it possible that the new addition is a carrier?

DAVE

most koi carry whitespot asymptomatically it take a variety of conditions to break it out its probably that you would have had this outbreak even if you had not introduced a new fish

the important thing is you dealing with it and probably on top of it now

dunc