Carp Edema Virus aka Sleepy Koi Disease

a koi pond with many fish swimming in it affected by koi sleepy disease.

Our office has seen in increase of Carp Edema Virus cases this year and we want you koi owners to know what to look out for. Also known as Sleepy Koi Disease, this virus can have deadly consequences for your fish.

a koi pond with carp edema virus

What is Carp Edema Virus?

Carp Edema Virus (CEV) is an emerging pox virus that infects koi. It was first noted in the USA in the 1990s and has spread throughout the world. It is also known as Koi Sleepy Disease or Koi Sleeping Sickness due to its common clinical sign.

What are the clinical signs?

Given its other name of Koi Sleepy Disease, a common clinical sign that may be seen with Carp Edema Virus is that your fish are all laying on their sides, still breathing, but appear to be “asleep.” With stimulation, such as a tap in their immediate area or a push of a net, they will get up and start swimming again. After a few swims, they will sink and fall over again. With the recent cases of this disease, our office has none in which this clinical sign was apparent.

Other clinical signs include:

  • Sudden deaths (70-100%)
  • Increased slime coat
  • Increased respirations
  • Lethargy
  • Decreased appetite
  • Secondary infections (ulcers)
  • Mottled/pale gills

Many of these clinical signs can resemble other koi viral disease, such as Koi Herpes Virus and Spring Viremia of Carp, so testing is essential.

How do I know if my fish are sick?

If you see any of the above clinical signs or have lost multiple fish, the first call should be to your aquatic veterinarian. There is a PCR test available for Carp Edema Virus that your veterinarian can submit samples for. UC Davis has a great carp panel that will test Carp Edema Virus, Koi Herpes Virus, Spring Viremia of Carp and Carp Pox using the same sample. You cannot submit samples without a veterinarian sending them to the lab. Other differentials for multiple deaths and above clinical signs include poor water quality, parasites or bacteria. Your veterinarian will know if viral testing is necessary.

How do koi catch CEV?

Your koi will catch viruses from an apparently healthy fish being added to their system. This new addition may appear perfectly healthy, and may never get sick themselves, but the stress of transport and introduction to a new system will cause them to shed the virus, which can be caught by the other koi in your system.

How do I treat my fish?

Since it is viral, there is NO TREATMENT for Carp Edema Virus. Raising your salinity to 5ppt can help alleviate clinical signs and decrease morbidity and mortality, but it will NOT CURE your fish. Any fish that survive are suspected carriers for life.

What is the best method to prevent viruses getting into my system?

“The best offense is a good defense.” The only way to keep viruses from affecting your current koi is to keep ALL new additions, regardless of where they came from (“reputable dealers” are not exempt), for 4-6 weeks. After a few weeks, depending on the water temperature, your veterinarian can submit samples for testing, ensuring that your new fish are not carrying any diseases (or parasites, or bacteria, for that matter). Quarantining fish in this manner can save the lives of all of your fish.

Click here to read more about Carp Edema Virus.

Subscribe to get more tips and info about fish.

Share with your friends!

Leave a Comment

Your email address will not be published. Required fields are marked *

Get This FREE Download

The Top 10 Mistakes Fish Owners Make

We'll never share your email. Unsubscribe any time. 

Top 10 Mistakes

Get This FREE Download

The Top 10 Mistakes Fish Owners Make

We'll never share your email. Unsubscribe any time. 

Top 10 Mistakes
Share to...