What is Anguillid Herpesvirus (AngHV-1)?
AngHV-1 is a virus that affects eels only. It does not infect carp, trout, perch, pike, or any other species.
It has been found in European eels, Japanese eels, and American eels.
The virus becomes most active in warm water (about 10–26°C), so disease problems usually happen in summer and early autumn, especially when fish are stressed.
What does AngHV-1 do to eels?
Eels with this virus may:
- become slow or tired (lethargic)
- swim near the surface or edges
- show reddened fins
- have patchy or mottled skin
The virus mainly attacks the gills, causing cell death and loss of normal gill structure.
This makes it harder for eels to breathe and fight off other infections.
Inside the body, the virus can also damage organs and lead to:
- inflammation
- organ failure
- weakness
- death
Where is AngHV-1 found?
Only a few confirmed outbreaks have been recorded in wild UK eels, but the virus is believed to be more widespread across Europe.
Some eels may carry the virus without showing symptoms.
Because of this, researchers are running surveys to:
- find out how common the virus is
- see which rivers are most at risk
- understand how the virus spreads
This helps prevent disease from being transferred when fish are moved or stocked.
Other viruses that affect eels
There are three major eel viruses:
- AngHV-1 — Herpesvirus
- EVE — Eel Virus European (aquabirnavirus)
- EVEX — European X Rhabdovirus
AngHV-1 and EVEX have both caused deaths in wild eels in England.
All three viruses can reduce swimming ability, which may prevent eels from making their long journey to the Sargasso Sea to spawn.
Why this matters for eel management
Healthy eels are essential for:
- stocking
- migration
- long-term species survival
Disease can reduce the chances of silver eels successfully reaching the sea.