WANT TO KNOW IF YOU HAVE SVC? 

by E L Johnson, October, 2002

Lots of "hubbub" lately about SVC and koi viruses in general. Viruses in Koi are not unlike viruses in people. They tend to be contagious and there are no direct "cures". This article pertains to SVC in particular.

"SVC" stands for "Spring Viraemia of Carp". This is a viral infection which is regarded very seriously in Britain. This viral infection is easily spread from fish to fish through the water. Until this year, SVC was not considered to be a pathogen in the US, mostly because of a lack of testing, and partly because of it's prior dismissal in the literature.

The virus' scientific name is "Rhabdovirus carpio". This virus is potently immune suppressive and opens the fish to almost any secondary pathogenic invader. It was speculated by Ken Wolf (USFWS) that these secondary infections are what cause mortalities in infected fish. This information may be considered "dated" now, and the severity, morbidity and mortality of these SVC infections may have been updated towards more dire (worse) numbers.

There is no known cure for SVC however some clinicians believe that the majority of affected fish will survive an SVC outbreak if concurrent parasitisms and bacterial infections are controlled.

This season, I received three batches of fish this Spring which were possibly from the groups of fish which were purportedly affected with SVC from Kernersville NC. In all three of these groups, clearance of the abundant Costial infections and injection of antimicrobials were curative and mortalities were under 30% or less.

It's important to note that we did NOT confirm that these fish were from the actual SVC infected groups but the timetables overlapped. This brings me to the main point of my article here.

Spring Viraemia of Carp (rhabdovirus carpio) is a Class Three pathogen. This means that in all instances, the virus and infections which are discovered by various laboratories, are reportable to the proper officials by law. Currently, the protocol when the virus is discovered is the destruction of the affected and exposed fish, plus the quarantine of your facilities for an undetermined amount of time.

What this means:

How to go out of business instantly:

Submit fish to a lab where SVC testing is run, and have the fish diagnosed positive for SVC. Your inventory will be summarily destroyed and your facilities shut down. It could be a minimum of twenty four months before you can sell fish again. Tough luck for you. Sorry.

How to get rid of every fish you own as a private hobbyist:

Submit fish to a lab where SVC testing is run, and have the fish diagnosed positive for SVC. Your collection will be destroyed and you will not be able to transport fish from your premises, the same as if you were retail.

The point of this article is to alert you that if you're a retailer concerned that your fish have SVC, and you submit a test for that virus, you will be signing your own death-warrant as a business should the test result come back a positive. If you are a hobbyist, the diagnosis of SVC will result in the death of all your fish, whereas suffering silently with the virus and taking evasive measures with medications and optimal environmental support may spare a considerable number of your fish.

The objective of the 'test-and-slaughter' approach, coupled with the quarantines, is to limit the infections, and stop their spread. I laud the efforts of the regulatory agencies in this area. I understand their goals. But businesses and hobbyists should know that successfully accomplishing the diagnosis of this disease in their stocks is equivalent to flushing their fish, their businesses, and their hobby-participation right down the toilet.

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SDK:- So under the new program of the USDA no Koi Farmer or Koi Keeper in the USA need to fear material loss if he reports suspect cases of SVC in his ponds. Hopefully the spread of SVC will be contained more effectively in the USA like it has been done in the UK for quite some time.

SPAIN, Wednesday, November 13, 2002 reported on www.fis.com

After 10 years of research, Galician scientists have discovered a highly effective and non-polluting natural medicine that can be used in aquaculture. 

Professors Jose Luis Sanchez and Ricardo Riguera from Compostela University (UCS) Aquaculture Institute have succeeded in developing the sector's first natural antibiotics. The discovery - which is being patented and is not available to producers yet - is a revolutionary milestone for aquaculture.

The scientists produced the antibiotics from marine bacteria, which they found some months ago while working on a nutrition study with scallop and oyster larvae. They discovered that at certain times the cultures improved and that this improvement occurred when there were bacteria populations present, reports La Voz de Galicia.

At this point, they isolated molecules and were able to synthesise this totally natural medicine that will be used exclusively to fight some of the pathogens that affect farmed fish and molluscs. At present, the medicine used to combat these diseases are strong pollutants and therefore banned.

In an official statement, UCS says the research findings resulted in five new molecules being patented so that they can be later sold to the public. These products, which are easily degradable, require a dose that is 10 times smaller than is currently used and are extremely effective in combating high levels of mortality in farmed fish and molluscs. 

The products are easy to synthesise in the lab without any need to cultivate the bacteria, say the scientists, so the process is quick and cheap. All that remains now is to make the antibiotics available to fish farmers.

SDK:- Somehow there is an odd ring to this report: "(discovery after) 10 years of research....marine bacteria...found some months ago while working on a nutrition study." But perhaps just the overactive imagination of a copy writer. 

Nevertheless, good news, but please let us all treat antibiotics with the respect they deserve. Use it wisely, use it sparingly and use it according to prescription.

Liming materials are used widely in aquaculture to neutralize acidity in pond soil and water, to increase alkalinity and hardness of water, to destroy disease carriers in soil, and for other purposes. Nevertheless, many who use these materials do not understand their properties. 

Commercial lime come in various forms and preparations and vary greatly in quality in most countries. Farmers should acquaint themselves with the properties of available liming materials and insist that vendors provide data.

The ability of a liming material to react with acidity is called the neutralizing value. Pure calcium carbonate is the standard for comparison with other compounds and dosages are normally given as such. The product the farmer buys can however contain in varying degree the carbonates, hydroxides and oxides of both calcium and magnesium, all dependent on the origin and treatment of the delivered product. The net effect can be that the neutralizing value can be as high as double that of the standard calcium carbonate. The resulting incorrect dosing can lead to unexpecting high pH levels.

Know your lime. Your treatment can be completely ineffective for your intended use or you may be killing your fish and not know what is happening. Both ways you are none the wiser and out of pocket.