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Chestnut lamprey

Ichthyomyzon castaneus

What do they look like?

Chestnut lampreys do not have a jaw. In addition, their skeleton is made of cartilage and they do not have a true vertebra. They have a long body with an adult length of 125 to 250 mm. Chestnut lampreys tend to have a dark coloration. Most adults are brown and black, with a cream or beige colored belly. Chestnut lampreys have one large dorsal fin for movement. These lampreys have a sucking disk on their mouths that contains rows of teeth, this species feeds by using the suction produced by these sucking disks. Chestnut lampreys have a single nostril between their eyes and seven gill pores directly behind their eyes. (Hall, 1963; Hardisty and Potter, 1971)

  • Sexual Dimorphism
  • sexes shaped differently
  • Range mass
    30 to 40 g
    1.06 to 1.41 oz
  • Range length
    125 to 271 mm
    4.92 to 10.67 in

Where do they live?

Chestnut lampreys are native to central North America. Their range stretches as far north as the Hudson Bay in Canada and as far South as the Gulf of Mexico. In the United States, chestnut lampreys are found from Texas to Georgia and from Minnesota to Michigan. In Canada, these lampreys are found from Saskatchewan to Ontario. Chestnut lampreys keep such a large range through the use of the Mississippi and Missouri River networks. Their range mirrors the movements of their host fishes. Along with their host fishes, chestnut lampreys move south when the weather becomes colder. (Becker, 1983; Hall, 1963; Scott and Crossman, 1979; Starrett, et al., 1960)

What kind of habitat do they need?

Chestnut lampreys tend to live in lakes and rivers. They are parasitic and dependent on larger host fish, due to this; they tend to share an area with larger predators. Chestnut lampreys are active at night and need rocks and river banks to rest near during the day. In order to spawn, chestnut lampreys move to a river or lake where they can build a spawning nest on the rock bed. Their spawning areas are found upstream of silt beds with areas where their young can bury themselves until adulthood. (Becker, 1983; Hall, 1963; Renaud, et al., 1996)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

How do they grow?

Chestnut lampreys have two life stages, larval and adult. They stay in the larval phase for an average of 5 to 7 years. After hatching, they float downstream and bury themselves in a layer of silt. Over the next few years, they filter feed on diatoms and other small particles in the sediment. At around 3 to 4 years, they begin to develop their sucking disk. The addition of teeth around their mouth opening allows for parasitic feeding and is needed for their development into adulthood. Once they enter their adult phase, they are capable of sucking blood and other nutrients from host fish using their sucking disk. Chestnut lampreys live an average of another one to two years in their adult stage. Once their parasitic stage is complete, chestnut lampreys spawn and die shortly thereafter. (Hall, 1963)

How do they reproduce?

Male chestnut lampreys spawn with multiple females. After spawning, both males and females die. Females attract mates using pheromones (chemicals) during spawning. (Case, 1970; Hall, 1963)

Spawning occurs in late spring, once the water temperature increases to 10°C (50°F). When spawning season begins, chestnut lampreys migrate upstream to smaller tributaries. Adult lampreys build nests using their sucker disks to clear rocks and debris. Once cleared, the female attaches to a rock and the male wraps his tail around hers to fertilize the eggs. Thousands of eggs are released into the nest. The eggs hatch about 2 weeks after being fertilized, after which they drift downstream and bury into soft sediment until they mature. Adults die shortly after spawning. (Case, 1970; Manion and Hanson, 1980)

  • How often does reproduction occur?
    Chestnut lampreys breed once in their lifetime.
  • Breeding season
    These lampreys breed from late spring to summer.
  • Average number of offspring
  • Range age at sexual or reproductive maturity (female)
    5 to 7 years
  • Range age at sexual or reproductive maturity (male)
    5 to 7 years

Since adults die shortly after spawning, chestnut lampreys show little to no parental care, aside from building a nest. (Case, 1970; Manion and Hanson, 1980)

  • Parental Investment
  • no parental involvement

How long do they live?

Chestnut lampreys live in a larval state for 5 to 7 years, during which they develop the ability to feed off of larger host fish. When they mature, lampreys feed for a period of one to two years. Once the time comes to spawn, lampreys migrate to a suitable area, spawn, and die shortly afterwards. Their total lifespan is about 6 to 9 years. (Becker, 1983; Hall, 1963)

  • Typical lifespan
    Status: wild
    6 to 9 years

How do they behave?

Juvenile lampreys are mostly inactive and stay burrowed until they mature. The behavior of adult chestnut lampreys is centered on their parasitic nature. Lamprey behavior is focused on finding a host, so they often move with larger fish. Once a host is found, they feed off of the fish until they are nourished. This rarely causes the host to die, as lampreys detach before that happens. (Hall, 1963; Hardisty and Potter, 1971)

Home Range

Adult chestnut lampreys live within the home range of their host fish. (Hall, 1963)

How do they communicate with each other?

Chestnut lampreys are only known to communicate during spawning, this includes using pheromone (chemical) signals to help them find mates. (Manion and Hanson, 1980)

What do they eat?

During their larval stage, chestnut lampreys filter feed on diatoms in the sediment where they are buried. These diatoms include tiny algae particles and protozoa. As adults, chestnut lampreys are parasitic on many different fish species such as carp, trout, pike, suckers, paddlefish, sturgeons, catfish, and sunfish. Their feeding season stretches from April to October. The species of their host fish varies based on where they are and what is available. Lampreys feed on blood, liquefied skin, and other bodily fluids from their host fish. Although fish do not usually die as a result of the parasitic relationship, it can sometimes cause a secondary infection. Likewise, multiple parasitic interactions can result in the death of a host fish. (Becker, 1983; Hardisty and Potter, 1971)

  • Animal Foods
  • fish
  • blood
  • body fluids
  • Plant Foods
  • algae
  • Other Foods
  • microbes

What eats them and how do they avoid being eaten?

Adult chestnut lampreys have no known predators, however, in their larval stage, chestnut lampreys are preyed upon by burbot and brown trout. (Hall, 1963)

What roles do they have in the ecosystem?

As parasites, chestnut lampreys have a large effect on their ecosystem, including helping to remove weaker fish from the population. (Becker, 1983)

Species (or larger taxonomic groups) used as hosts by this species

Do they cause problems?

Chestnut lampreys can have a negative effect on the fishing industry when populations become too large. Fish that host chestnut lampreys are often left unhealthy and are no longer good for game or commercial fishing. Likewise, healthy fish can become harder to find when lamprey populations are high. (Becker, 1983)

How do they interact with us?

Filter feeding larvae can be used to indicate water quality. Since chestnut lamprey larvae filter feed in the sediment, smaller than expected populations could indicate pollution in the water or sediment. (Hall, 1963)

Are they endangered?

According to the IUCN redlist, chestnut lampreys are considered a species of least concern. Their population is stable without any major threats. There are no efforts in place to protect the species. (Lanteigne, 1992; Smith and Darwall, 2013)


Timothy Acciaioli (author), University of Michigan-Ann Arbor, Jeff Schaeffer (editor), University of Michigan-Ann Arbor, Lauren Sallan (editor), University of Michigan-Ann Arbor, Leila Siciliano Martina (editor), Animal Diversity Web Staff.


Becker, G. 1983. Fishes of Wisconsin. Madison, WI: University of Wisconsin Press.

Case, B. 1970. Spawning behavior of the chestnut lamprey Ichthyomyzon castaneus. Journal of the Fisheries Research Board of Canada, 27(10): 1872-1874.

Hall, J. 1963. An ecological study of the chestnut lamprey, Ichthyomyzon castaneus (Girard), in the Manistee River, Michigan. Ann Arbor, MI: University of Michigan.

Hardisty, M., I. Potter. 1971. The Biology of Lampreys. London and New York, NY: Academic Press.

Lanteigne, J. 1992. Status of the chestnut lamprey, Ichthyomyzon castaneus, in Canada. Canadian Field-Naturalist, 106(2): 14-18.

Manion, P., L. Hanson. 1980. Spawning Behavior and Fecundity of Lampreys from the Upper Three Great Lakes. Canadian Journal of Fisheries and Aquatic Sciences, 37(11): 1635-1640.

Renaud, C., S. Ribey, F. Chapleau. 1996. Four records of the chestnut lamprey, Ichthyomyzon castaneus, new to Ontario. Canadian Field-Naturalist, 110: 450-453.

Scott, W., E. Crossman. 1979. Freshwater Fishes of Canada. Fisheries Research Board of Canada, 84: 966.

Smith, K., W. Darwall. 2013. "IUCN Redlist" (On-line). Ichthyomyzon castaneus. Accessed October 30, 2013 at

Starrett, W., W. Harth, P. Smith. 1960. Parasitic lampreys of the genus Icthyomyzon in the Rivers of Illinois. Copeia, Copeia 1960: 337-346.

University of Michigan Museum of ZoologyNational Science Foundation

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Acciaioli, T. 2014. "Ichthyomyzon castaneus" (On-line), Animal Diversity Web. Accessed May 25, 2024 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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