Are Your Carp Healthy?

I Certainly Hope So! We spend a great deal of time of time, effort and money to ensure that our fish are healthy and would never send anything out that we weren’t a 100% happy with.

We have strict bio-security controls on our fish farm to ensure that the fish we produce are healthy and strong when we deliver them to you. We have a huge amount of fish at the farm and one of the easiest ways to infect them would be by introducing infected fish there. We get around this by completely banning any stock introductions that haven’t come from our own hatchery. The only fish taken onto the farm are tiny fry, the sort of size where you carry 100,000 in a bucket, which are grown in our hatchery each spring. No other fish are ever taken onto the farm to avoid the possibility of unwittingly introducing a parasite or other pathogen. Even the brood fish are kept elsewhere.

All the equipment we use to harvest and grade fish is dedicated to the farm and never used anywhere else, even the staff have separate waders and clothing for use on the farm and another set for work elsewhere. The farm is organised so that each pond is drained down, limed and cultivated regularly to eradicate any risk of disease or parasite carry over between ponds or between crops of fish. We do not allow any fishermen onto the farm to ensure that no parasites are introduced from their nets or other kit.

By ensuring that the fry taken onto the farm are completely healthy and then ensuring that nothing else, neither fish, equipment or un necessary people, are ever allowed onto the farm whilst they are growing, we reduce the risk of ever contracting serious health problems. This is called Bio security and it works.

Fish Health Testing and Checks

There is no point in going to all the trouble of growing these fish for up to three years on the farm if they are not healthy when we come to sell them and so through the whole production process we keep a very close eye on a range of potential health issues. In addition to our own regular examinations, we employ an independent fish health specialist to examine our fish and provide us with a Fish Health Certificate. Currently the specialist we use is Ian Welby of the company Blueroof. Ian was formerly a Fish Health Scientist at the Environment Agency Fish Health Labs at Huntingdon. These Fish Health Certificates are lodged with The Environment Agency at Huntingdon and are used in the Section 30 Stocking consent process.

Viruses – The Big Killers

• Spring viraemia of Carp (SVC)

  Whilst parasites are irritating to fish, they are rarely fatal. The biggest killers of carp are viruses. Spring Viraemia of Carp (SVC) first popped up in the early 90’s and can be devastating. It is a notifiable disease, which means that if it occurs or is suspected of being present, CEFAS swing into action in an attempt to eradicate it. Generally, it occurs after the introduction of infected fish and will often kill the indigenous fish and not those introduced. SVC occurs widely in continental Europe which is why we are not allowed to import carp from Europe into the UK, a position we whole heartedly support. It is alleged by the authorities that many of the SVC outbreaks in the UK would appear to be associated with illegal imports of big carp, which continue to enter this country. The problem is that folk going into the market and waving a lot of cash around will be offered ‘English’ fish, which in some cases may have been imported and ‘laundered’. Very often such fish come without paperwork or stocking consents, so if a disease outbreak occurs, the poor unfortunate owner has to deny any knowledge of a stocking to avoid prosecution by the EA. How one gets around this, I am not quite sure.

  In any event, SVC is a serious disease but actually pretty rare and much less of a problem that we originally feared. As part of the new European Directive requirement to regularly and routinely screen UK Registered Fish Farms for SVC (Spring Viraemia of Carp), we provide government Fish Health Inspectors from CEFAS with samples of fish from across the farm to check for SVC each Spring. These tests are very accurate and have always been negative.

• Koi Herpes Virus (KHV)

  KHV is more of a problem. The virus was identified in 2003 and is now known to have been responsible for large scale fish kills all the way back to 1996. Unlike SVC, KHV can lay dormant in fish for many, many years before something triggers an infection and a disease outbreak occurs. The problem here is that there are probably hundreds of fisheries around the country, which have unwittingly been stocked with infected fish before KHV was identified. Many of these fisheries will have had no problems at all but given the right conditions, hot weather, poor water quality and some other stressor, like very heavy angling pressure, disease outbreaks do occur and can devastate fisheries. This pattern appears consistent with disease outbreaks in 2006, which was very warm and affected mainly intensive commercial fisheries. 2007, much cooler and the UK had fewer problems.

  There are good tests for KHV that will show the virus when there is actually a disease outbreak and fish are dying. The bad news is that there is not yet a really good test for identifying fish which are carrying KHV in the latent stage. There is an indirect test, which looks for the anti bodies that fish produce when exposed to the virus. The authorities are working pretty hard on developing new and more accurate tests.

  With SVC there appears to be pretty much a direct connection between a disease outbreak and stocking infected fish.

  There have been a dozen or so new cases of KHV reported in each of the last few years but there has been no clear explanation as to how the fisheries become infected. There has been work to show that the virus can be moved from one fishery to the next on angler’s nets. Birds such as cormorants have also been implicated. It is clear that the virus could be introduced by stocking but there is no easy or cheap way to determine whether the fish you are about to introduce are carriers.

  Buying fish from a proper fish farm that is regularly scrutinised like our own is certainly a major way to reduce the risk. Buying from a dealer who could easily be selling you fish he is completely unaware are carriers of KHV is clearly a much more risky route. Some dealers try to get around this by selling you fish from their ‘farm’. There are very few proper farms in the UK that are solely dedicated to producing a fish from fry to adult but there are quite a lot of small sites which are actually holding sites for dealers who bring fish in feed them for a bit then say that they are produced at their site. The current law says that when a fish has been in a pond for six months, that is where it is deemed to have come from. So an imported fish from Israel, put into a pond for six months is now legally English!

Contrast this with buying from a dealer or a ‘farm’ run by a dealer (for which read holding ponds), who sources his fish from anywhere he can net them, brings them home, puts them all in the same ponds, accumulating and mixing up all sorts of health problems over time. There will be little scrutiny of his fish, each batch is quite different. Just because you had a good batch last year, doesn’t mean they will be good this time (they came from a completely different place). You will have little or no control over where they have actually come from, regardless what the paperwork says. In effect you are playing the fishy version of Russian roulette, not just with the fish you actually buy but also with the stock already in your fishery that you are proposing to mix these new fish up with!

For more information about the fish we supply at Sport & Leisure Fisheries, call us on 01952 585002 or fill out our enquiry form on our Contact Us page.