Brook Lamprey Identification Guide

Key identification features

• Small, slender, eel-like body, usually only 10-15 cm long as an adult
• Two dorsal fins set close together or narrowly separated by a shallow notch
• Oral sucker disc present but with small, blunt, degenerate teeth that are too weak for feeding
• Uniform grayish-brown to olive coloring along the back, paling to a lighter belly
• No paired fins, consistent with all lampreys
• Adults do not feed; they emerge from the sediment only briefly to spawn and then die

Common look-alikes

• Sea lamprey and river lamprey grow much larger and retain sharp, well-developed feeding teeth on their oral disc.
• Larval lampreys of any species look similar as blind, toothless burrowers, but brook lamprey adults never develop the enlarged, strongly armed disc seen in parasitic species.

Where you'll see one

Brook lampreys live in small, clean, gravel- or sand-bottomed streams and headwaters, where their larvae spend several years burrowed in silty banks before a short-lived, non-feeding adult stage confined entirely to freshwater.