Chestnut lamprey
Ichthyomyzon castaneus Girard, 1858

member of the Lamprey Family (Petromyzontidae)

Sunrise River, Chisago County, Minnesota 6 May 1988

Chestnut Lamprey and Suckermouth Minnow 

photos by Konrad P. Schmidt













What's In a Name?
Chestnut lamprey: refers to the color of the fish  

Ichthyomyzon (ick-thee-oh-my´-zon) means "sucker of fish" in Greek
castaneus (cass-tan´-ee-us) means "having chestnut color" in Greek


    Where Do They Live?
Chestnut lampreys live in certain large streams and small rivers of the Red, St. Croix, and lower Mississippi river systems. Adults can be found in just about any habitat within these streams, where they are often found attached to the sides of their prey (see "What do they eat"). The larvae (called ammocetes, pronounced "ammo-seats") bury themselves in soft silt and muck in areas of quiet water with some aquatic vegetation.


How Big Do They Get?
How Long Do They Live?
Chestnut lampreys grow to about 200-250 mm (8-10 in) long and weigh 30-40 g (1.1-1.4 oz). Like other lampreys, chestnuts live a long time as larvae, probably 5 to 7 years, (but we are not sure). As adults they may live for another 2 years.

    What Do They Eat?
The long-living larvae (called ammocetes, pronounced "ammo-seats") filters tiny algae (desmids and diatoms) and protozoa (ameba, etc.) from the soft sediments and water just above them. As adults, chestnuts attach themselves to the sides of various fishes, including a variety of suckers, catfishes, and sturgeons. They chew a hole into the flesh of the host fish, consuming a small bit of its muscle and a lot of body fluids.

What Eats Them?
Burbot and brown trout have been known to eat larval chestnut lamprey. We are not sure what, if anything, preys on the adults.


How Do They Reproduce?
Chestnut lampreys migrate upstream and into smaller tributary streams to spawn. In Minnesota, spawning takes place in May and June after water temperatures reach 12-13° C (about 55° F). They seek out gravel or sand bottoms in areas of medium current. There the male lampreys remove pebbles with their "sucker" discs to make a large spawning nest. The nest is used by many males and females, who spawn in pairs after attaching themselves with their "suckers" to rocks. Each female may lay anywhere from 20 to 40 eggs in one spawning act. A female will spawn many times over several days until she has deposited all her eggs. A single female may lay 24,000-107,000 depending on her size and health. Gravel displaced by spawning lampreys covers the fertilized eggs. The adults die shortly after they are done spawning.

We do not know how long it takes for the eggs (which are really embryos) to hatch. The newly hatched ammocetes, (pronounced "ammo-seats") drift downstream to softer bottoms and burrow into the muck. They eat, grow, and develop over several years (maybe 5-7) before they metamorphose (change into) adults.


Conservation and Management
We do not know what the impact of chestnut lamprey populations is on sport fishes, and we do not attempt to manage this species. Some anglers view chestnut lampreys as a nuisance because they sometimes find them attached to the sport fish they catch.




Permission is granted for the non-commercial educational or scientific use of the text and images on this Web document. Please credit the author or authors listed below.

Photographs by Konrad P. Schmidt
Text by Nicole Paulson & Jay T. Hatch in cooperation with
the Minnesota Department of Natural Resources' MinnAqua Aquatic Program

This page developed with funds from the
MinnAqua Program (Minnesota Department of Natural Resources, Division of Fisheries)
and the
Sport Fish Restoration Program (Fish and Wildlife Service, US Department of the Interior)

Maintained by Jay T. Hatch
General College and James Ford Bell Museum of Natural History
University of Minnesota, Minneapolis/St. Paul

Last updated 23 October 2002