Chestnut Lamprey Identification Guide
Recognize a Chestnut Lamprey by its rich brown coloring, single dorsal fin, and bicuspid inner teeth.
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Key identification features
- Medium-sized, eel-like body, generally 25-40 cm as an adult
- A single, continuous dorsal fin rather than two clearly separated fins
- Rich chestnut-brown to dark olive coloring over the back and sides, duller than the closely related silver lamprey
- Oral sucker disc with well-developed teeth, including bicuspid (two-pointed) inner lateral teeth
- Single nostril on the top of the head, as in all lampreys
- Functional feeding disc adapted for attaching to and rasping host fish
Common look-alikes
- Silver lamprey looks similar but has brighter, more silvery sides and mostly single-pointed (unicuspid) teeth instead of bicuspid inner teeth.
- Northern brook lamprey shares the single continuous dorsal fin of the same genus but is smaller and non-parasitic with weak, blunt teeth.
Where you'll see one
Chestnut lamprey inhabits medium to large rivers and lakes across the central and eastern United States and southern Canada, where adults parasitize fish in open water before migrating into smaller tributary streams with gravel bottoms to spawn.
Frequently asked questions
How do I distinguish Chestnut Lamprey from Silver Lamprey?
Coloring and teeth are the key: chestnut lamprey is a duller brown with bicuspid inner teeth, while silver lamprey is brighter silvery with mostly single-pointed teeth.
How do I know a lamprey belongs to the same genus as Chestnut Lamprey?
Check the dorsal fin: species in this genus, including chestnut, silver, and northern brook lamprey, all have one continuous dorsal fin rather than two separate ones.