Brook lampreys are the smallest of British lampreys at just 15cm long. They have blunt horny teeth in a funnel shaped mouth.
The adults are small eel-like fish with two dorsal fins whilst the larvae are actually larger than the adult fish!
Brook lampreys particularly like freshwater streams with mud, silt or sandy bottoms.
The larvae live for over 6 years in a burrow in the river or stream bed. Their slithery shape enables them to disappear completely in just a couple of seconds! The adult brook lampreys die straight after spawning.
Herbivore - The larvae feed by filtering fine organic particles such as algae and detritus. The adults do not feed at all as they have short lives ending after they have spawned!
The Brook Lamprey is considered vulnerable but not critically endangered. As it needs to move upstream for spawning it is affected by barriers to migration such as dams. Other issues include flooding, disturbance of spawning habitats and eutrophication (algal blooms). These problems are likely to get worse due to climate change and water abstraction.
Because brook lampreys are protected by law their needs must be taken into account when managing rivers and water resources or taking decisions about development.