River Lamprey

Lampetra fluviatilis

  1. Wildlife
  2. Freshwater fish
  3. River Lamprey


Some of the most primitive vertebrates still alive today, river lampreys are small, eel-like fish with toothed, sucker-mouths. They use this sucker to attach to other fish, rasping away at the flesh and feeding on bodily fluids. They also feed on carrion. Adult river lampreys live in the sea and return to freshwater to spawn. When they find a suitable breeding place, the male will attach to the female using his sucker and wrap his body around hers, ensuring he fertilises the eggs as she lays them. Females can lay up to 25,000 eggs with a succession of males attached to her. After spawning the adults die; the young hatch but spend several years buried in the silt. When they finally reach adult stage they will migrate out to sea.

How to identify

The river lamprey is bluish-grey on the back and sides and white underneath. It can be distinguished from other lamprey by its two separate dorsal fins and the small number of teeth around its sucker.

Where to find it

Found throughout the country.

When to find it

  • January
  • February
  • March
  • April
  • May
  • June
  • July
  • August
  • September
  • October
  • November
  • December

How can people help

UK populations of river lamprey are extremely important if this species is to survive in Europe, as pollution and changing land use are detrimentally affecting its numbers. Working with landowners, politicians, statutory bodies and water companies to promote wildlife-friendly practices, The Wildlife Trusts are working towards a Living Landscape: a network of habitats and wildlife corridors across town and country which are good for both wildlife and people. You can support this greener future by joining your local Wildlife Trust.

Species information

Common name
River Lamprey
Latin name
Lampetra fluviatilis
Freshwater fish
Length: up to 50cm Weight: up to 150g Average Lifespan: up to 10 years
Conservation status
Classified as a Priority Species in the UK Biodiversity Action Plan.