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Chub minnow

Couesius plumbeus

What do they look like?

Lake chub have a long body that is nearly round in cross section. Their back and upper sides are lead gray. They are silver to silver-white below the lateral line, with some darkened scales on their sides, giving them a speckled look. Their snout is rounded and slightly overhangs their mouth. Their mouth is large, almost reaching the margin of their eyes, with a long whisker (barbell) in each corner. (Becker, 1983; Brown, et al., 1970)

Male and female lake chub can be told apart based on their appearance. Males have larger pectoral fins, which are long and rounded with a gap between the end of the pectoral fin and the beginning of the pelvic fin. During breeding, males have a faint rosy color at the corner of their mouth, on their upper lip, and above their lip groove. Likewise, the base of their pelvic fin has a rosy spot, the side of their body has a faint rosy stripe, and there is a black lateral stripe during courtship. Females are larger and have short pectoral fins with a gap between the end of the pectoral fin and the beginning of the pelvic fin. During breeding, females have a rosy color at the base of their pectoral fin. Males and females also develop skin bumps (tubercles) during breeding. (Becker, 1983; Brown, et al., 1970)

  • Sexual Dimorphism
  • female larger
  • Average length
    127 mm
    5.00 in

Where do they live?

Lake chub (Couesius plumbeus) have the widest northern distribution of any North American minnow. These fish are found widely throughout Canada. In the northern areas of the United States, they are found in the upper areas of the Missouri River Basin, the Great Lakes region, and the northern Atlantic slope drainages. They are also found in eastern Iowa, northern Nebraska, and north-central Colorado. (Becker, 1983; Bestegen, et al., 1991; Stasiak, 2006; Wells, 1980)

What kind of habitat do they need?

Lake chub prefer cool, shallow waters, however, they can also be found in streams and lakes of all sizes throughout their range. They most commonly live in lakes in the southern part of their range, and in rivers in the northern part. In lakes, they are often found near shores with sandy bottoms and some large-sized boulders. In streams they are more commonly found at river-mouths, at depths of about 1 meter or less. (Becker, 1983)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

How do they grow?

Lake chub eggs have a dark golden yolk and range in diameter from 1.8 to 2.4 mm after being fertilized. Newly hatched larvae range in length from 5.8 to 6.4 mm and are only partially developed. Larvae body proportions change quickly until they reach about 9 mm in length, after which they grow more slowly. Lake chub are usually mature by the age of three and very few live past age four, although lake chub older than four have been found. (Becker, 1983; Fuiman and Baker, 1981)

How do they reproduce?

During spawning, male lake chub pursue females. When a female is near a spawning-ready male or males, the males charge her from beneath, causing the female to swim upward, sometimes breaking the water surface. The male swims next to the female, and if multiple males are still present, they swim side by side to compete for the female. During this courtship process, the male's lateral body stripe becomes darker and more distinct, and their mouth opens and closes rapidly. This continues until the female swims to a rock and the remaining male moves against her until her eggs are released. (Brown, et al., 1970)

Lake chub spawn in the spring in their more southern ranges and later in the summer in their more northern ranges. Lake chub can spawn in many habitats, including river shallows, along rocky shores, in lake shoals, and on silt, leaves, gravel, or rocks. However, they most often enter creeks and streams or travel along lakeshores to spawn, although river-breeding chub do not mix with lake-breeding chub. Spawning migrations can range from less than 0.8 km (0.5 miles) to up to 1.6 km (1 mi). Temperature has a major impact on a male's ability to mate; they require low temperatures (5-12°C, 41-53.6°F) during the winter before spawning. (Becker, 1983; Brown, et al., 1970; Stasiak, 2006)

  • How often does reproduction occur?
    Breeding generally occurs several times per minute, however, each act of spawning only lasts about one second.
  • Breeding season
    Depending on the region, lake chub spawning occurs during the spring or summer months.
  • Range number of offspring
    800 to 2400
  • Range time to hatching
    8 to 10 days
  • Average age at sexual or reproductive maturity (female)
    Age class III years
  • Average age at sexual or reproductive maturity (male)
    Age class III years

Lake chub are not known to build nests, nor are they known to give any parental care to their eggs or young. (Becker, 1983)

  • Parental Investment
  • no parental involvement

How long do they live?

Very few lake chub live past the age of four years. However, their average lifespan is about five years and they have been known to live up to seven years. Female lake chub grow faster and likely live longer than males. (Coad, et al., 1995; Scott and Crossman, 1973)

  • Range lifespan
    Status: wild
    7 (high) years
  • Average lifespan
    Status: wild
    4 years

How do they behave?

Lake chub are social and form large schools to migrate to spawning grounds together in the spring, but shift to deeper waters in the summer for cooler temperatures. This species is usually active during the day. However, when they are migrating and predators are more aware of them, they may become active during the night, probably to avoid predation. (Reebs, 2001; Smith, 2010)

Home Range

These fish migrate for spawning each year. These migrations can range from less than 0.8 km (0.5 miles) to up to 1.6 km (1 mi). (Becker, 1983; Brown, et al., 1970; Stasiak, 2006)

How do they communicate with each other?

Unlike some fish with whiskers, lake chub likely do not have external taste buds. Therefore these fish likely perceive their environment by sight. (Davis and Miller, 1967)

What do they eat?

Young lake chub eat small aquatic crustaceans. They continue eating these crustaceans as they age, however, older lake chub mostly eat insects, although some also eat small amounts of snails and fish eggs. Because lake chub do not have external taste buds, they forage mostly based on sight. (Becker, 1983; Davis and Miller, 1967)

  • Animal Foods
  • fish
  • eggs
  • insects
  • aquatic crustaceans

What eats them and how do they avoid being eaten?

Lake chub are preyed on by fishes and birds such as lake trout, burbot, walleyes, and northern pike, as well as mergansers, kingfishers, and common loons. They also have several mammalian predators such as minks, martens, otters, fishers, and raccoons. To avoid predators in areas where they are especially vulnerable, such as streams during spawning, these fish can become more active during the night. Lake chub larvae and young also have their own predators including diving beetles, giant water bugs, and dragonflies. (Coad, et al., 1995; Reebs, 2001; Scott and Crossman, 1973; Stasiak, 2006)

What roles do they have in the ecosystem?

Lake chub may host many types of small parasites such as the larval form of trematodes (Diplostomulum and Posthodiplostomum minimum), the adult form of nematodes (Rhabdochona), acanthocephalans (Echinorhynchus salmonis), Protozoa, cestodes, glochidia, and crustaceans (Ergasilus caeruleus). In many cases, lake chub are actually intermediate hosts, with the final development phase taking place inside birds and other fishes. (Scott and Crossman, 1973)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

Lake chub may get in the way of fishing, as they are often caught instead of the more desirable brook trout. (Becker, 1983)

How do they interact with us?

Lake chub are commonly used as live bait for early spring fishing, especially in Canada. In addition, smaller lake chub are often caught and eaten under the mistaken impression that they are smelt. (Coad, et al., 1995; Scott and Crossman, 1973)

  • Ways that people benefit from these animals:
  • food

Are they endangered?

According to the IUCN Red List, lake chub are a species of least concern due to their large range, large population size, stable population trends, and lack of major threats. (NatureServe, 2013)


Annalise Povolo (author), University of Michigan-Ann Arbor, Lauren Sallan (editor), University of Michigan-Ann Arbor, Jeff Schaeffer (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.

Bestegen, K., K. Fausch, S. Riley. 1991. Rediscovery of a relict southern population of Lake Chub, Couesius plumbeus, in Colorado. The Southwestern Naturalist, 31/1: 125-127.

Brown, J., U. Hammer, G. Koshinsky. 1970. Breeding biology of the lake chub, Couesius plumbeus, at Lac la Ronge, Saskatchewan. Journal of the Fisheries Board of Canada, 27/6: 1005-1015.

Coad, B., H. Waszczuk, I. Labignan. 1995. Encyclopedia of Canadian Fishes. Waterdown, Ontario: Canadian Museum of Nature and Canadian Sportfishing Productions Inc.

Davis, B., R. Miller. 1967. Brain patterns in minnows of the genus Hybopsis in relation to feeding habits and habitat. Copeia, 1: 1-39.

Fuiman, L., J. Baker. 1981. Larval stages of the lake chub, Couesius plumbeus. Canadian Journal of Zoology, 59/2: 218-224.

NatureServe, 2013. "IUCN Redlist of Threatened Species" (On-line). Couesius plumbeus. Accessed July 21, 2014 at

Reebs, S. 2001. Fish Behavior in the Aquarium and in the Wild. United States of America: Cornell University Press.

Scott, W., E. Crossman. 1973. Lake chub: Couesius plumbeus (agassiz). Pp. 401-406 in Freshwater Fishes of Canada, Vol. 184, 1 Edition. Canada: The Bryant Press Limited.

Smith, G. 2010. Guide to Great Lakes Fishes. United States of America: The University of Michigan Press.

Stasiak, R. 2006. "USDA Forest Service, Rocky Mountain Region" (On-line). Lake Chub (Couesius plumbeus): A Technical Conservation Assessment. Accessed December 03, 2013 at

Wells, A. 1980. Couesius plumbeus (Agassiz), Lake Chub. Pp. 854 in D Lee, ed. Atlas of North American Freshwater Fishes, Vol. 1980, 12 Edition. Raleigh, North Carolina: North Carolina State Museum of Natural History.

University of Michigan Museum of ZoologyNational Science Foundation

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Povolo, A. 2014. "Couesius plumbeus" (On-line), Animal Diversity Web. Accessed April 13, 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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