Koi herpes virus page with info on the disease and diagnostics

The virus initially attacks the gills. From there it spreads to the kidneys. Damage to the gills is the most visible sign with high level of deaths. The signs seen can be caused by many different diseases. High numbers of deaths increase the suspicion of KHV while specific testing is required to diagnose the disease (see below).

  • Most commonly seen between June and October when pond water is reaching the required temperatures
  • Infected fish will not develop the disease until the water reaches at least 16 degrees C.
  • Survivors are carriers and will pass the infection on to new fish

All suspicious disease outbreaks in carp species (including Koi) should be tested for KHV

Testing for Koi Herpes Virus (KHV)

The most accurate test on dead Koi for KHV is a PCR test.

We will collect the sample free of charge if the fish is delivered to us. However there is a charge if euthanasia and/or disposal of the body is required. The fish must be chilled and placed in a fridge soon after death (contact us for advise).

Instructions for collecting your own sample

The best sample to collect is a sample from kidney liver and gill on the same swab. This gives the best chance of identifying KHV if it is present.

Live fish sampling

  • From a live diseased fish a gill swab can be used but with just this there will be a percentage of false negatives
  • Open the gill cover to expose the red gill arches inside
  • Insert a sterile swab under the gill cover
  • Roll it across the gill arches until the swab is pink to red with cellular debris
  • Immediately place back in the tube without touching and send in to us

The sample will be ok for several days, but the urgency usually is in diagnosing the problem as soon as possible.

Sampling from a dead diseased fish

  • Aseptically collect kidney, liver spleen and gill(approximately tenth of a teaspoon sized pieces)
  • Place in a sterile sample pot and keep refrigerated and send to us

These are the tissues usually loaded with virus

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