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Central mudminnow

Umbra limi

What do they look like?

Central mudminnow adult sizes range between 50 to 115 mm. The average adult size is 60 mm and the maximum adult length is 140 mm. Average length of fish that are 1 year old is 41.5 mm. The cross-section of the body is round. The snout is stubby with a terminal mouth. The mouth is filled with very tiny teeth. The dorsal fin is set back towards the posterior half. The tain fin is rounded. The anal fin is larger than the pelvic and longer in males, almost reaching the tail fin. Males also develop a blue-green coloration on the anal fin during spawning season.

Overall coloration is dark olive-green to brown-black with 14 vertical dark brown bars along the sides. The top of the head and cheeks are scaled. There is a prominent, vertical, dusky bar at the base of the tail. The upper surface is yellow to white. Central mudminnows can be mistaken for banded killifish. Differentiation between the two species can be made by examining the mouth; banded killifish have "supraterminal" mouths (mouths on the bottom of their faces), whereas common mudminnows have "terminal" mouths (mouths on the end of their faces). (Apllegate, 1943; Becker, 1983; Tomelleri and Eberle, 1990)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • male more colorful
  • sexes shaped differently
  • Range length
    50 to 115 mm
    1.97 to 4.53 in
  • Average length
    60 mm
    2.36 in

Where do they live?

Mudpuppies are native to North America and are found in both Canada and the United States. Their native range includes the Great Lakes, Hudson Bay, the St. Lawrence, Red, and Mississippi River basins from Quebec to Manitoba and south to central Ohio, Tennessee, and northeastern Arkansas. There are isolated populations in the Missouri River basin in South Dakota and Iowa. Montana, Oklahoma, and Texas have had reports of isolated, non-native occurrences. Reports of introduced mudpuppy populations or individuals in eastern North America, including Connecticut, Massachusetts, and Maine have been made in the last twenty years. (Schilling, et al., 2006)

What kind of habitat do they need?

Central mudminnows are resilient and thrive in waters with dense vegetation, low oxygen levels, slow water flow, and thick layers of organic material at the bottom. Their name is derived from the Latin umbra meaning shadow or phantom and limi meaning mud. They are most commonly found in water less than five meters deep. In Wisconsin, this species is commonly found among cattail, waterweed, eel grass, bulrush, yellow water lily, water buttercup, and filamentous algae. They are a predominantly bottom-dwelling fish.

During periods of fast water flow, central mudminnows move from their normal habitats and venture into the flooded areas along the banks to avoid strong water currents. They have the ability to breath air and thus can survive for short periods of time when there is no oxygen in the water. (Becker, 1983; Chilton, et al., 1984; Klinger, et al., 1982; Peckham and Dineen, 1957; Rahel and Nutzman, 1994; Schilling, et al., 2006; Tomelleri and Eberle, 1990; Tonn and Paszkowski, 1986)

  • Aquatic Biomes
  • benthic
  • lakes and ponds
  • rivers and streams
  • temporary pools
  • Range depth
    5 (high) m
    16.40 (high) ft

How do they grow?

Fry (baby fish) are see-through and approximately 5 mm when they hatch. Fry become pigmented and dark on their 16th day after hatching. When young reach 30 mm they move from flooded edges and pools back into the main stream where there is deeper water. The young continue to grow and may reach 55 mm by October. Central mudminnows continue to grow throughout their entire lives. (Apllegate, 1943; Becker, 1983; Peckham and Dineen, 1957)

How do they reproduce?

There is little information on mating behavior for central mudminnows.

Spawning is most likely prompted by warming water temperatures and flooding in spring. Preferred water temperature for spawning is 12.8⁰C but can occur at up to 15.3⁰C. Many central mudminnows migrate to flooded areas during spring. Spawning habitat is preferably flooded stream margins and pools with slow or no flow. Eggs are laid underwater on the river bottom. Females stick each egg to a piece of vegetation. Females lay 425 to 450 eggs on average. Eggs are yellow or orange and measure about 1.6 mm in diameter. There is some egg guarding behavior by the female. The eggs hatch 6 days after being laid. (Becker, 1983; Peckham and Dineen, 1957; Tomelleri and Eberle, 1990)

  • How often does reproduction occur?
    Central mudminnows are thought to breed once a year.
  • Breeding season
    Spawning is most likely prompted by warming water temperatures and flooding in spring.
  • Range number of offspring
    425 to 450
  • Average number of offspring
  • Average time to hatching
    6 days

There is little to no parental investment for central mudminnows. Females may guard their eggs, but no other parental behaviors have been observed. (Becker, 1983)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • female

How long do they live?

It is thought that central mudminnows live for approximately 7 to 9 years. (Apllegate, 1943; Becker, 1983)

  • Typical lifespan
    Status: wild
    7 to 9 years

How do they behave?

Central mudminnows seem to prefer to be near a group of other central mudminnows, therefore showing social versus solitary behavior. Grouping together may help to avoid predators or find food. Research has shown that central mudminnows tend to form groups of 12 or more.

When threatened, they flee into soft sediment and ooze when threatened. Central mudminnows have special body structures that allow them to breath air. In winter, central mudminnows can survive when the water lacks oxygen. These fish can breath air from tiny air bubbles trapped under ice-covered lakes.

Central mudminnows also spend time foraging for insect prey in oxygen-poor lakes. This is sometimes accomplished closing their gills and essentially holding their breath. They can only do this for a short period of time, however, before they run out of air.

This ability to breath air during winter allows them to remain active all year long, unlike most fish. Central mudminnows continue to grow during winter and can prepare early for spring spawning. This is an advantage because their eggs are laid early and can hatch early. Thus central mudminnow fry (baby fish) are well developed by their first, harsh winter. (Becker, 1983; Chilton, et al., 1984; Jenkins and Miller, 2006; Klinger, et al., 1982; Peckham and Dineen, 1957; Rahel and Nutzman, 1994; Tonn and Paszkowski, 1986)

Home Range

Home range sizes of central mudminnows are not reported.

How do they communicate with each other?

Research has shown that central mudminnows use visual clues to compare the size of shoals (groups of fish). It has been suggested that these fish also use smell or touch to analyze shoals and decide which shoals to join. Further studies are needed to understand communication in central mudminnows. (Jenkins and Miller, 2006)

What do they eat?

Central mudminnows are primarily bottom feeders and generally carnivorous. Central mudminnow diet includes small crustaceans, amphipods, isopod crustaceans, crayfish, long-legged fly larvae, crane flies, mayflies, earthworms and a variety of insect larvae and small fishes.

Juvenile winter diet during their first year included small crustaceans, and crustacean and insect larvae. Young fish (19 mm) have been observed feeding on newly hatched snails, fly larvae and fishes. Small central mudminnows were not found foraging in oxygen-poor waters that larger central mudminnows use. Some research has shown that only female central mudminnows eat fish. (Becker, 1983; Chilton, et al., 1984; Peckham and Dineen, 1957; Rahel and Nutzman, 1994)

  • Animal Foods
  • fish
  • eggs
  • terrestrial non-insect arthropods
  • terrestrial worms
  • aquatic or marine worms
  • aquatic crustaceans
  • zooplankton

What eats them and how do they avoid being eaten?

Central mudminnows are preyed on by other fish including grass pickerel, chain pickerel, northern pike, sunfishes, catfishes and sculpins. Their chief predators are mottled sculpin. Land predators include herons, muskrats and foxes.

Central mudminnows escape predators by burying themselves in the mud or leaves on lake bottoms. Their brownish coloration helps to camouflage them with their surroundings so that predators cannot find them. (Becker, 1983; Peckham and Dineen, 1957; Tonn and Paszkowski, 1986)

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Since central mudminnows are able to survive in low oxygen conditions when many other species cannot, they play an important role in their ecosystems. Their preference for, and success in, heavily vegetated habitats also makes them a specialist. They are an important prey item for many species. (Peckham and Dineen, 1957; Tonn and Paszkowski, 1986)

Do they cause problems?

There are no known negative effects of central mudminnows on humans.

How do they interact with us?

Fishermen are familiar with central mudminnows as hardy bait fish. Their ability to breath air and overall tolerance of extreme environmental conditions make them an excellent bucket fish. These characteristics also make them good fish for laboratory studies. Long-lived, attractive, and easy to care for, central mudminnows are an interesting aquarium fish. These fish can easily be trained to take food pieces from people. (Becker, 1983; Jenkins and Miller, 2006; Schilling, et al., 2006)

Are they endangered?

Currently, central mudminnows are listed as state threatened in Kentucky, state endangered in South Dakota, and are a candidate species in Pennsylvania. They are protected or of special concern in Missouri and North Dakota. They are abundant in rivers and lakes of Michigan. (Tomelleri and Eberle, 1990)


Alexis Growe-Raney (author), Northern Michigan University, Rachelle Sterling (editor), Special Projects, Jill Leonard (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.


Apllegate, V. 1943. Partial analysis of growth in a population of Umbra limi (Kirtland). Copeia, 1943: 92-97.

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

Chilton, G., K. Martin, J. Gee. 1984. Winter feeding: an adaptive strategy broadening the niche of the central mudminnow, Umbra limi. Environmental Biology of Fishes, 10: 215-219.

Jenkins, J., B. Miller. 2006. Shoaling behavior in the central mudminnow (Umbra limi). American Midland Naturalist, 158: 226-232.

Klinger, S., J. Magnuson, G. Gallepp. 1982. Survival mechanisms of the central mudminnow (Umbra limi) and brook stickleback (Culaea inconstans) for low oxygen in water. Environmental Biology of Fishes, 7: 113-120.

Peckham, R., C. Dineen. 1957. Ecology of the central mudminnow, Umbra limi (Kirtland). American Midland Naturalist, 58: 222-231.

Rahel, F., J. Nutzman. 1994. Foraging in a lethal environment: fish predation in hypoxic waters of a stratified lake. Ecology, 75: 1246-1253.

Schilling, E., D. Halliwell, A. Gullo, J. Markowsky. 2006. First records of Umbra limi (central mudminnow in Maine. Northeastern Naturalist, 13: 287-290.

Tomelleri, J., M. Eberle. 1990. Fishes of the Centeral United States. Lawrence, KS: University of Kansas Press.

Tonn, W., C. Paszkowski. 1986. Size limited predation, winterkill and the organization of Umbra-Perca fish assemblages. Canadian Journal of Fisheries and Aquatic Sciences, 43: 194-202.

University of Michigan Museum of ZoologyNational Science Foundation

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Growe-Raney, A. 2011. "Umbra limi" (On-line), Animal Diversity Web. Accessed April 22, 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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