Randy LeFever, Owner and President of Blue Ridge Fish Hatchery, offers some advice regarding carp pox, and what it may mean for your fish.
Carp pox is a herpesvirus that affects koi. Effects are primarily seen in the cold winter months, when a koi's immune system is less active. Carp pox is not to be confused with KHV (Koi Herpesvirus). Where KHV can result in massive losses, carp pox is relatively benign and typically not life-threatening. Symptomatic fish will have hard, waxy-looking lesions, usually around the head and shoulders and on the fins.
But what to do about it? Well, the recommended treatment is… do nothing… and wait for the water to warm.
There are no chemicals (antibiotic or otherwise) that will have a positive effect on fish infected with carp pox. This is because viruses do their damage by inserting themselves into normal cells and killing them, but not before instructing that cells' machinery to duplicate the virus. So any attempt to destroy virus particles will necessarily kill the host as well.
So what's a koi keeper to do? The only thing you can do is support the koi's immune system so that it can destroy the virus on it's own. In the case of Carp pox, this means simply providing your fish with good water quality and waiting for the water to warm. Then your koi's immune system will work it's magic and the carp pox lesions will disappear.
Dealers, you can find a copy of this article in the Downloads section. Print it out, display it in your store, or offer it as a handout to educate your customers!