Korean Lamprey Identification Guide

Key identification features

• Small body, generally under about 20 cm at maturity
• Two low dorsal fins set close together toward the rear of the body
• Small oral disc with reduced, blunt teeth since adults stop feeding after transforming
• Dark brown to grey-brown coloration above, lightening toward a pale belly
• Slender, scaleless, eel-like build with no paired fins anywhere on the body
• Larvae are blind and toothless, spending years buried in fine stream sediment before a brief adult stage

Common look-alikes

• Larger parasitic lampreys sharing nearby drainages keep strong, well-developed feeding teeth and grow noticeably larger than this species.
• Other small brook lampreys across East Asia look very similar, so confirming the exact river system in Korea is often the deciding factor.
• Eels and other slender freshwater fish share the general shape but have jaws, paired fins, and visible scales, none of which lampreys possess.

Where you'll see one

The Korean Lamprey lives entirely in fresh water, favoring small streams and tributaries across the Korean peninsula, where it burrows into silty or sandy substrate as a larva before a short, non-feeding adult stage focused on spawning.