Ichthyomyzon castaneus
    Chestnut Lamprey

Chestnut Lamprey

Flora, fauna, earth, and sky...
The natural history of the northwoods



  • Ichthyomyzon, from the Greek, "fish to suck", a reference to its feeding habits.
  • castaneus, from the Greek, "chestnut colored"
  • Common name from its color
  • Other common names include: Brown Lamprey, Lamper, Lamprey, Lamprey Eel


  • Kingdom Animalia
    • Phylum Chordata, animals with a spinal chord
    • Subphylum Vertebrata, animals with a backbone
      • Superclass Agnatha
      • Class Cephalaspidomorphi
      • Subclass Cephalaspidomorpha
        • Order Petromyzontiformes
          • Family Petromyzontidae, lampreys
            • Genus Ichthyomyzon, lampreys
  • Lamprey are among the most primitive of living vertebrates, having first appeared in the fossil record some 300 million years ago.


  • A slender, primitive, eel-like fish
  • Length 8"-13"
  • Coloration
    • dark grey to olive or yellow brown above
    • sides, belly, and fins lighter
    • adults blue-black at spawning time
  • Body
    • smooth leathery skin with no scales
    • poorly developed cartilaginous skeleton (boneless)
    • myomeres (body segments) clearly defined, numbering 51 to 54, usually more than 52, between the last gill slit and anus.
    • digestive tract well developed.
    • dorsal fin continuous, with shallow notch but not divided into two separate fins or double lobed.
  • Head
    • ends in a buccal funnel
    • mouth a jaw-less, sucking disc; wider than the body when expanded.
    • teeth slender and sharp, in circular row around the mouth; nearly all bicuspid (having two points).
    • tongue rasplike
    • single nostril between the eyes.
    • gill pores seven in number, in a straight line immediately behind the eye.


  • Easily distinguished from other Northwoods fishes by its eel-like shape and sucking mouthparts.
  • Distinguished from the Silver Lamprey (Ichthyomyzon unicuspis) by:
    • continuous dorsal fin without the double lobes
    • mouth a sucking disc, but the circumoral teeth are nearly all bicuspid, or two pointed.
    • 51 to 54, usually more than 52, myomeres or segments in the body between the last gill slit and the anus. Silver Lamprey has 49-52.
  • Distinguished from the Northern Brook Lamprey (Ichthyomyzon fossor) by:
    • much larger size. Northern Brook Lamprey only 6" in length.


  • Generally distributed along the Great Lakes and in tributaries of the Mississippi and Ohio Rivers from Minnesota to Arkansas.
  • Also records from the Hudson Bay drainage.


  • Parasitic adults live in moderate-sized rivers and large creeks where they find their fish hosts, though generally in smaller bodies of water than the larger Silver Lamprey (Ichthyomyzon unicuspis).
  • Only active at night; during the day, they hide from the light under rocks or under the cover of river banks
  • Larval ammocoetes require sand and dark mud, relatively free of clay silt.
  • chestnut lampreys inhabit
  • Areas suitable for spawning tend to disappear from siltation and pollution. The deterioration of river environments threatens their food supply and toxic chemicals can cause mortality. Eutrophication can cause mortality in the young


  • Adult lamprey are parasitic upon a wide variety of stream fishes, attaching to host with a suction-cup mouth and drilling into the fish with its tongue and teeth. This creates a wound through which the lamprey feeds on body fluids and muscles of the host fish.
  • Remains attached to host over a long period of time unless brushed off by the distressed fish. Fishes almost colorless from the loss of blood have been observed with several lampreys attached, but they seldom kill the host since that would deprive them of their food source.
  • Adults attack a variety of fish, generally choosing smaller fish than the larger Silver Lamprey (Ichthyomyzon unicuspis).
  • Ammocoetes (larval young) feed on drifting plankton and detritus.


  • The earliest known lampreys, Mayomyzon, are from the Pennsylvanian Period, about 300 million years ago. They are thought to be related to an extinct group of jawless fishes, the ostracoderms, which flourished earlier.
  • Populations of native lamprey are generally in decline throughout their range.


  • Parasitic feeding habits limit their appeal to anglers.
  • These animals are never taken by hook-and-line; hence they are of no importance to the anglers, except possibly as bait for other fish.
  • May have some value as forage for predatory game fish.


  • Spawning occurs in late spring and early summer when the water temperature reaches 50º F. Adults ascend small tributary streams to spawn among rocks in sand and gravel bottom riffles.
  • Nests are built in shallow gravelly riffles. The adults constantly work on the nests with short interruptions for spawning. The female attaches to a rock and the male attaches to her head, wrapping his tail around hers to bring the genital openings close together. The pair vibrates as the eggs and sperm are released; then they separate and return to nest building.
  • Adults die soon after spawning, the eggs hatching about two weeks later.
  • Larvae (known as ammocetes) resemble parents except that they are blind and the mouth hooded, toothless, and provided with a fine-mesh tissue sieve.
  • After hatching, the ammocoetes drift downstream to quiet waters where they live in small burrows in the bottom ooze for 7-9 years. At this stage they are not parasitic, feeding largely on algae and microscopic animals.
  • Ammocetes metamorphose in the fall, remain in the streams over winter, then move downstream to rivers and lakes in search of hosts.
  • After two years as parasites, the adults return upstream to spawn and die.


  • The native lamprey species of the genus Ichthyomyzon should not be confused with the exotic and destructive Sea Lamprey (Petromyzon marinus), which wreaked havoc with native game fish in the Great Lakes before vigorous control measures brought it to check. The native lamprey have evolved with, and live in balance with, their host populations.
  • Status
    • Identified as a vulnerable species in adjacent boreal Canada.
    • Listed as a species of special concern in Georgia, Kentucky, Nebraska
    • Listed as Threatened in Iowa and Kansas


  • Lampreys, a general article from the Tree of Life

Boreal border

Last updated on 13 November 1999