Hallo Everyone

I've just registered on this forum, and have been reading extensively. Glad that I ended up here, but sad that it had to be because of KHV.

We have a large pond in Pretoria and have been working on it and improving it over the last fifteen years. As hobby koi keepers we have learned a lot by trial and error but have also been very happy go lucky about things like disease. And we have been incredibly lucky to have healty koi and only minor pond issues all this time.

I'm sure that none of you need me to tell you that keeping koi is a big commitment in time and money. We love our pond and spend time there every day.

Early in January my husband bought a few koi from a shop in Jhb and we added them to our pond with about 60 other koi, some of which we have had since the early days of our pond. After a week all the new koi died within a matter of 48 hours. A few days later the other fish started getting sick. We have now lost almost all our koi and looking at the progression of the disease, and the fact that none of the usual remedies had any effect there is no doubt in my mind that we have KHV. Although we were vaguely aware of KHV we never thought it was that common, or something we should be worried about. Since doing some research I realize that we have been living in a fools paradise.

Right now we are devastated by our loss. In time, when we start restocking our pond, you will find me reading and asking about quarantine and how to buy from dealers in such a way that a tragedy is not likely to happen again.

Megan

Hi and welcome to the forum.

Sorry to hear about your koi.

Khv is an ugly thing and you should quarantine all your new koi.

nardus

Thank you Nardus, we are certainly learning the hard way. Took some more young koi out of the pond this morning. All but two of the big ones are gone.
Megan

I think you should get them tested for KHV.

If they do have KHV.

There is no treatment or cure.

Its hard to do but you will need to euthanize them.

Even if they survive they will still be carriers and as they will effect any new fish you place in the same water as them.

I am not quite sure how you will clean your pond to make sure the KHV is dead in your pond as well.

I would assume you get rid of all the pond water 1st.

Fill it up again and add a ridiculous amount of pp and salt to kill everything.

Hopefully one of the KOI gurus will along shortly to advise you on what to do.

Hi Megan

I am very sorry for your loss.

It is not necessarily KHV although quite likely, based on what you said. It can also be a bacterial infection although it normally takes longer before the fish die off. The new koi were possibly introduced to a type of bacteria in your pond to which they had no immunity, and they started to die. This might have increased the load of that type of bacteria, and your own fish started to die because their immune system could only handle a certain amount of that bad bacteria.

The main idea of quarantine procedures is to allow two batches of koi (current and new) to gradually get used to a new type of bacteria and to build up an immunity, before releasing the new batch into your pond.

I would send samples of at least three fish to MDS to find out if is KHV, and if positive, you will have to kill all fish, disinfect the pond with Virkon S and Chlorine, let it stand for a while, and start all over. The procedure to send samples is plain and simple and is covered under this category of the forum.

Hallo Paul
Thanks for your comments.
In addition to the koi we have Red Cap Oranda and a few fantail goldfish in the pond. The other fish are thriving, no signs of distress and no deaths. This is one of the things that makes me think that it must be KHV and not bacteria or a fungus. The Oranda are very sensitive, they are usually the ones to get sick.
Since the damage is done, we have decided to wait it out. If all the koi die, we will euthanaze the other fish, and nuke the pond before we start over. (I read somewhere yesterday that goldfish can also be carriers of the virus).
If some koi survive, we are going to have them tested before we take the decision to euthanase.
There are two smaller ponds with tiny koi, hatchlings from our big pond. There is no sign of sickness in either of the small ponds so far, and we have been careful not to have any contact between the ponds since the first fish got sick. Do we risk keeping them?
The sick pond contains some rare water plants. Would I need to destroy the plants, or could I move them to a pond without fish and re-introduce the plants to the big pond after a period?
In case you are wondering about the abundance of ponds, plants and fish... we live on a small holding.
Megan

Hi Megan,

There is no way to know if you have had KHV. You must test for this you cant guess.

There are other diseases that can kill your koi collection. This cross infection of fish is well known. As Paul says it could easily be a bacterial cross infection.

I find it strange that one group of fish died first. i.e. the new fish.

KHV has mutated over the years and koi seem to be taking longer to die. 10 years ago you had a 80% mortality within a week or so.

Back to other infections: The bacterial infections are becoming stronger. And you have to identify the strain of bacteria and then get an antibiotic for that strain of bacteria. Very often the wrong antiboitic is used.

Costia can also wipe out the collection just as effectively and quickly as KHV or a bacterial infection. A leading koi health advisor in the UK believes more koi are killed from Costia infections than KHV.

All these diseases are triggered by stress. Handling stress is a major cause of disease out breaks in koi collections.

There is a growing swell of opinion overseas that killing all the remaining koi in a collection is not necessary. IF they have KHV. There is a growing belief that a very high percentage of koi carry the KHV virus in a latent form even before they get to you collection. So the chances of the koi having latent KHV before an outbreak is great. Further there is no guarantee that is a koi has latent KHV there will be an outbreak.

KHV is a herpes virus. Humans carry a type of herpes virus in a latent form. About 98% of the human population carry herpes virus in a latent form but it only affects a small percentage of the population.

Yes, KHV in koi is deadly but there are numerous cases of koi keepers (here in South Africa) keeping survivors of a proven KHV outbreak with success. And then a later stage successfully introducing in koi.

So yes, if your disease outbreak is KHV - and you must test several fish for this, it is possible to keep the survivors. (and I am going to get a lot of flack for saying this).

The figures for the last 6 or 7 years on KHV infections show a decrease in infection levels and a decrease in moralities.

But remember KHV must be proven first by lab tests. And there are lot of other diseases and parasites that if left untreated can cause a lot of fatalities.

The fact that the fish did not respond to the treatment you gave them might indicate that the wrong treatment was given and not KHV.

Quarantine your fish to prevent any further problems from getting into your collection.

Chris

Hallo Chris
Thank you for your input. If we still have any fish left in a few days and they show signs of surviving, we will definitely order some tests.
My husband and I are thinking in circles. On one hand we don't want to test because if the tests come back positive, we would need to destroy the remaining fish, that would feel like murder. But looking at it soberly, it is probably best to know for sure.
I realize that without testing one can not say for a fact whether it is KHV, but I have been working with fish and treating minor disease problems all these years and never come accross anything this horrible.
Apart from a raise in the water temperature due to the recent heat wave, and introducing the new fish, there have been no stressors in the pond. The water is clean and all the non-koi fish have stayed healthy throughout this episode.
I am going to hang on to that little thread of hope about latent KHV that you offered, I have read similar statements on other sites.
Since we do not sell our fish, or even give them away, if we have latent KHV in our ponds we are not a risk to the koi community.
On the other hand, we have just lost fifteen years worth of building a collection of (to us) stunning fish, and I never want to experience this again. Agressive measures now might save heartbreak in future. And quarantine of any new fish that ever comes to live with us from now on!
Megan

Hi Megan,

There is more we do not know about KHV than we do.

Because viruses spread so very easily, in all forms of life in the world, and they cannot be cured, they are a real problem.

The argument put forward by some institutions is the since the first discovered out break of KHV in the UK in 1996 in the koi and carp community we still have it and it has not been able to contain be with culling.

Infection rates are definitely down these last few years. They are sitting around 8% positive tests of all submitted samples in South Africa. We cannot compare this infection rate to any other country as we are the only country I know of who have virtually all the tests done at one lab! It is unfortunately unfortunately not going to go away. So we must manage it - just as we must manage other diseases and parasites.

So far the best method is to quarantine any new fish before you put them into your collection. This is also a good practice for isolating all diseases and parasites. If there is a outbreak and infection it can be contained in the quarantine pond and not spread to your fish.

If the new fish are well after some time then they are added to your main collection.

By the way they have found that a positive KHV testing koi can swim around with the fish collection quite happily. Something can - I do not say will - trigger it to become deadly.

There is also an immune response starting the the koi them selves. And as the virus mutates it appears to be coming less deadly.

Just think - a virus needs a living cell to replicate. So if a virus kills all the living cells it can replicate in it will no longer exist itself. (Remember KHV only affects carp and koi). Many be the virus has woke up to this fact. I hope so. Then koi can live with it just as we live with certain viruses in all human population.

So long as you never sell or give you koi away it may be a good idea to keep the survivors. If it was KHV it will then be contained in you collection. (And the survivors will probably have developed an immunity to it.

On the bright side - it could be great fun building your collection.

Chris