Fish Active at night

Silver Lamprey

Ichthyomyzon unicuspis

iNaturalist Wikipedia

The silver lamprey is a remarkable 'living fossil' that has inhabited North American waterways for millions of years. This native jawless fish offers a unique glimpse into the ancient history of aquatic life.

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Quick Identification

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Size

15–39 cm (6–15 inches) in length; weight typically ranges from 15–150 grams (0.5–5.3 oz)

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Colors

Silvery-grey to tan or light blue-grey on the dorsal side; belly is white or pale yellowish; fins are often yellow-tinted

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Key Features

Suction-cup mouth with unicuspid (single-pointed) teeth
Long, eel-like body without paired fins
Single, continuous dorsal fin that is not notched
Seven circular gill openings on each side

When You’ll See Them

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Activity pattern Active at night

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Peak hours 10 PM - 4 AM

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Season May-June (during spawning migration)

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Diet Adults are parasitic, feeding on the blood and tissue fluids of various fish like trout, pike, and suckers; larvae (ammocoetes) are filter feeders that eat algae and detritus.

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Habitat Large rivers and lakes as adults; silty or sandy stream bottoms for the larval stage.

public Geographic range

Where Does the Silver Lamprey Live?

The silver lamprey is a native inhabitant of North America, found throughout the freshwater systems of the northern and central United States and southern Canada. Its core range includes the Great Lakes basin and the St. Lawrence River, extending westward through the Mississippi and Ohio River drainages to parts of Manitoba and Nebraska. While they are occasionally found as far south as Tennessee, they are most prevalent in the cool, interior waterways of the Midwest and Northeast.

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2 Countries

2.8M km² Range

Least Concern Conservation

US United States

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CA Canada

Marginal

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iNaturalist / Verified observation data

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Behavior

The silver lamprey is a parasitic, jawless fish that spends its adult life attached to larger host fish. Using its specialized suction-cup mouth and rasping tongue, it creates a small wound to feed on the blood and body fluids of its host. Unlike the invasive sea lamprey, the native silver lamprey has evolved alongside North American fish and rarely kills its host in healthy ecosystems.

As nocturnal creatures, they are most active under the cover of darkness, often moving between feeding grounds and resting spots. During the spring, adults undertake a significant migration upstream to clear, gravelly tributaries for spawning. Once they reach the spawning grounds, they use their mouths to move stones and create a nest (redd) before eventually dying after the eggs are laid.

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Camera Tips

Capturing the silver lamprey on camera is a rewarding challenge that requires a specialized underwater setup. Because they are aquatic and largely nocturnal, you should use a waterproof trail camera or an action camera with high-quality infrared (IR) night vision. The best time to see them is during their spring spawning run, typically from May to June. Position your camera in shallow, gravel-bottomed riffles of small to medium-sized streams where they gather to build nests.

For the most stable footage, mount your camera to a weighted base or a heavy rock using a specialized strap. Place the camera about 12-18 inches from the bottom, angled slightly upward toward a clear patch of gravel. This setup allows you to witness their unique nest-building behavior, where they use their suction mouths to haul stones. Since they are light-sensitive, avoid using white LED flashes; 'no-glow' or 940nm infrared is much better for observing their natural movements without scaring them away.

During the rest of the year, you might catch a silver lamprey 'hitchhiking' on a host fish. If you have a dock or a permanent underwater camera in a lake, focus your lens on areas where large fish like walleye or northern pike congregate. Look for a long, thin shape attached to the side or belly of these larger fish. To get the best clarity in murky river water, set your camera to record high-definition video (1080p or higher) with a high frame rate to capture the lamprey's distinct, undulating swimming pattern.

Similar Species

Species that look similar or are commonly confused with Silver Lamprey.

Sea Lamprey

Much larger (up to 40 inches) with a notched dorsal fin and mottled, dark skin compared to the silver lamprey's uniform color.

American Brook Lamprey

Non-parasitic and smaller; their teeth are poorly developed and they do not attach to other fish as adults.

Chestnut Lamprey

Very similar in appearance but has bicuspid (two-pointed) teeth in certain areas of the mouth disc, whereas the silver lamprey's teeth are unicuspid.

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Frequently Asked Questions

Silver lamprey are primarily nocturnal, meaning they are most active during the night. They use the darkness to avoid predators and to move between hosts or migration points. Your best chance of seeing them on camera is during the late-night hours between 10 PM and 4 AM.

Since they are aquatic, you can only 'attract' them if your property has a river or stream connected to the Great Lakes or Mississippi drainages. Maintaining a healthy, silt-free gravel bed in a stream can provide spawning habitat, but generally, they are found by placing cameras in their existing migratory paths during the spring.

As adults, silver lamprey are parasitic and feed on the blood and fluids of other fish. They attach to a host using their sucking disc and rasp away a small hole in the skin. In the larval stage, however, they are harmless filter-feeders that live in the mud and eat microscopic algae and organic debris.

They are not common in typical suburban ponds, but they are frequently found in larger rivers that pass through suburban landscapes. If you live near a major waterway in the Midwest or Northeast, they may be present, though they are rarely seen by humans due to their underwater, nocturnal nature.

The most obvious difference is the dorsal fin: silver lamprey have one long, continuous fin, while sea lamprey have a clearly notched dorsal fin that looks like two separate parts. Silver lamprey are also much smaller (under 15 inches) compared to the invasive sea lamprey, which can reach up to 40 inches.

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