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Silver Nitrate


Almost every person discussing viral infections these days are experts. Some are experts because they read other peoples studies, some have studied viral infections and some have heard about it and formed an opinion. I am saying this because right from the start I must confess that I am no expert. The raging debate currently is about the Lymphocystis virus and whether koi and therefore carp can be infected by this virus. I have seen quite a few authors swear that it can infect carp and describe it fairly accurately. Some just say that it cannot infect carp and that’s it. So for the poor hobbyist like me it becomes a nightmare.


In view of the above I will say, these rubbery warts that is rough to the touch that every keeper have seen on a koi somewhere, can be a Lymphocystis -, or Carp pox - or Epitheliocystis – or iridovirus - infection. It really does not matter. To me working with these kinds of lesions, it is solely of academic importance. The lesions are an eye-sore to keepers and have ruined the show career of many fish. For practical purposes I will call them “warts”


This link describes the positive results that I had with the treatment of warts with Acriflavine where I still described it as Lymphocystis.




Mostly these wart-like lesions on our koi appear when the fish are stressed or during winter when the water temperatures are low. We also know that when the temperatures go up, the warts may disappear spontaneously. Sometimes they will remain on a fish forever.

It is this last scenario that has prompted me to start looking for a treatment that will remove the wart effectively, although the chances of it reappearing when the fish are stressed remain.



The next option was nitrogen gas. The gas works like a charm, but the applicator cost a whopping R12000. I tried it on one fish, but soon realised that the tissue of a fish is vastly different that those of mammals. The warts were gone in a few days but a huge ulcer remained. On fins the tissue between the bone rays are “burned” and disintegrated within a few days

As said earlier, I stumbled onto this treatment purely by accident.


Please be assured that I have tested it and tested it ad nauseum. It removes viral lesions within a short time and has disinfected ulcers with one treatment. Sometimes the treatment was repeated after 3 days. The bottom line is that it works and I would like to share it with those that may need it.



The pencil is sold for the removal of warts on humans. It is a very small point and for its size, it is expensive. My experience with silver nitrate is that it turns the lesion black and sometimes this black is absorbed into the skin. As the skin regenerates, some of the silver nitrate is retained in the skin, ruining the fish.

This pencil consists of silver nitrate and Potassium Nitrate. The effect when you draw it over the lesion is that everything turns slowly white. No more worries about a black smudge on the skin once recovered.


What I normally do is to dry the affected area after the fish has been sedated. Just push the pencil point into the water of the tub and start rubbing the pencil across the lesion. Do not exert too much pressure. The areas covered by the pencil will turn a milky white.



Wait for 20 to 30 seconds and release the fish back into the pond. Do not try to seal the area. After a day or two the area will be a bit swollen and pink/red. Don’t be alarmed. Within a few days, the area will clear and the viral spot will disappear or the ulcer will start to recover.


Please note that the viral spots will disappear but it is not a cure for viral infections.

Last Updated on Wednesday, 29 February 2012 12:55