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Black mullet

Catostomus commersonii

What do they look like?

White suckers have a long, round body and grow to a length of about 241 mm and a maximum weight of about 2.5 kg. They are olive brown to black on their back and lighter, or white on their belly, with dusky or clear fins. Breeding males have a gold coloration on their backs and red (or less commonly cream or black) stripes across their sides. They have a toothless, sucking mouth and their lower lip is about twice as thick as their upper lip. White suckers have a shorter snout than their close relatives, longnose suckers. Young white suckers have dark blotches on their backs and sides. (Becker, 1983; "White Sucker Catostomus commersonii", 2013; "Catostomus commersonii", 2013; Page and Burr, 2011; "White Sucker, Catostomus commersonii (pictured) Longnose Sucker, Catostomus catostomus", 2013; Zimmerman, 2012)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • male more colorful
  • sexes shaped differently
  • Range mass
    2.5 (high) kg
    5.51 (high) lb
  • Average mass
    0.4 kg
    0.88 lb
  • Average length
    241 mm
    9.49 in

Where do they live?

White suckers (Catostomus commersonii) have a very large range, which includes over 2.5 million square kilometers, stretching from east of the Mackenzie River to Labrador in Canada, and into 40 states in the Eastern and Midwestern United States. These fish were also introduced to the Colorado River drainage basin. ("Catostomus commersonii", 2013; Page and Burr, 2011)

What kind of habitat do they need?

White suckers can live in many different habitats including streams, rivers, and lakes but are mostly found in small creeks with cold, clear water and small or medium-sized rivers. White suckers are also very tolerant of polluted, murky, and oxygen poor waters. They do not need dense vegetation and prefer temperatures between 11.8 and 20.6 degrees Celsius. (Becker, 1983; "White Sucker Catostomus commersonii", 2013; "Catostomus commersonii", 2013; Page and Burr, 2011; Zimmerman, 2012)

  • Aquatic Biomes
  • benthic
  • rivers and streams

How do they grow?

Embryos of white suckers develop quicker in warmer temperatures. Organs begin developing the day eggs are fertilized. Soon afterwards, the embryo becomes mobile, develop a circulatory system, and grow longer. Larvae hatch after about 5 to 7 days and are 21 to 25 mm in length, with slanted mouths and short intestines. When white suckers are less than 51 mm long, they feed in shallow water, 15 to 20 cm deep and along lake shores. In some populations, white suckers are mature by the time they are 2 years old, however, on average, suckers are mature by age 3. In other populations, males mature at a faster rate (2 years old) than females (3 years old) but all are mature by age 4. (Becker, 1983; Long and Ballard, 1976; McElman and Balon, 1980)

How do they reproduce?

After migrating upstream to a spawning area with quick running water and a gravely substrate, female white suckers settle to the bottom. Males, who arrived earlier, crowd around her until just two males find a place on either side of her. The three fish release sperm and eggs. After this quick (1.5 seconds) spawning, the female continues upstream to find two more male mates. The males likely also try to find a new mate. Males do not compete for females and usually ignore each other. (Becker, 1983)

White suckers spawn and breed upstream for six weeks in the spring, or early summer in northern areas. Upstream breeding usually happens at night and spawning usually lasts from April to early May. This happens shortly after ice melts from a spawning area, the length of spawning may be related to the water temperature. Male white suckers reach the spawning area earlier than females and outnumber them. White suckers do not build nests or defend a territory. The spawning area usually has quick running water and a gravely substrate, but spawning can sometimes occur in lakes if conditions are correct. Males may show "head trembling" behavior (vibrating their heads rapidly from side to side for a short time) towards a nearby female who has come to rest at the bottom of a rapid. Head trembling may also be directed at other males in the spawning area, although males do not fight for mates. Along with head trembling, male white suckers also spread their pectoral fins, extend their dorsal fin, and stick out their jaw. (Becker, 1983; Long and Ballard, 1976; "Catostomus commersonii", 2013; Zimmerman, 2012)

A single female can produces between 20,000 and 50,000 eggs, about 2 to 3 mm in diameter, which are usually fertilized by two males who float on either side of her during the spawning act. After spawning, the female swims upstream where she may mate with two more males. Due to this, a single female's eggs may be scattered in clumps over a large area. Their sticky eggs sink to the bottom of the spawning area and attach to gravel and other bottom material. After incubating for 5 to 7 days, the larvae hatch and stay in the area for 1 to 2 weeks. Their young migrate downstream about 1 month after spawning first occurred. Depending on the location, white suckers become sexually mature in 3 to 8 years, with males maturing faster than females. (Becker, 1983; Long and Ballard, 1976; "Catostomus commersonii", 2013; Zimmerman, 2012)

  • How often does reproduction occur?
    White suckers breed once a year.
  • Breeding season
    White suckers breed in the spring, usually from April to early May.
  • Range number of offspring
    20000 to 50000
  • Range time to hatching
    5 to 7 days
  • Range age at sexual or reproductive maturity (female)
    3 to 8 years
  • Range age at sexual or reproductive maturity (male)
    3 to 8 years

White suckers do not give any parental care.

  • Parental Investment
  • no parental involvement

How long do they live?

White suckers have a maximum life expectancy of about 17 years. ("White Sucker, Catostomus commersonii (pictured) Longnose Sucker, Catostomus catostomus", 2013)

  • Range lifespan
    Status: wild
    17 (high) years

How do they behave?

White suckers that are less than a year old form schools of several hundred fish. Adult and juvenile white suckers feed day and night but are more active at night when they move into shallower water. White suckers coordinate their movement so they are inshore during the evening and offshore by morning. In stream habitats, large white suckers can be found in deep pools. White suckers can be very good at moving long distances, in one such case, an individual white sucker ended up 56 km away from the area it was tagged 5 years before. (Becker, 1983)

Home Range

White suckers are not known to maintain a specific home range.

How do they communicate with each other?

When they are spawning, male white suckers may show "head trembling" behavior, by vibrating their heads rapidly from side to side towards a nearby female or to other males in the area. Males, however, do not compete with each other for mates. Along with head trembling, male white suckers may also spread their pectoral fins, extend their dorsal fin, and stick out their jaw. (Becker, 1983)

What do they eat?

Young white suckers feed on Protozoa, diatoms, small crustaceans, and midge larvae carried to them by currents. As white suckers age, their mouthparts move to their underside, allowing them to bottom-feed. As adults, they also feed on fish, fish eggs, plants, mollusks, insects, rotifers, chironomid larvae, mayflies, and algae. Adult white suckers mostly feed on zooplankton and invertebrates, but they may also specialize in one or the other. (Becker, 1983; Saint-Jacques, et al., 2000; Zimmerman, 2012)

  • Animal Foods
  • fish
  • eggs
  • insects
  • mollusks
  • aquatic or marine worms
  • aquatic crustaceans
  • other marine invertebrates
  • zooplankton

What eats them and how do they avoid being eaten?

White suckers are an important food source for several fish and land animal species. Muskellunges commonly eat white suckers during foraging. They are also eaten by bass, burbot, brook trout, and sea lamprey. Walleye and northern pike mostly eat their eggs or small white suckers up to about 203 mm long. Small white suckers are also eaten by bald eagles, herons, loons, and ospreys. Bears and other animals will feed on white suckers during spawning periods. (Becker, 1983)

What roles do they have in the ecosystem?

White suckers host the larval stage of the mollusks elktoes and alewife floaters. They prey on Protozoa, diatoms, small crustaceans, midge larvae, chironomid larvae, mayflies, fish, fish eggs, plants, mollusks, insects, rotifers, and algae. Additionally, they are preyed upon by muskellunges, bass, burbot, brook trout, sea lamprey, walleye, northern pike, bald eagles, herons, loons, ospreys, bears, and other animals. White suckers compete with yellow perch for invertebrate prey. Removing white suckers from areas with both species causes more invertebrates and fewer zooplankton to be eat by yellow perch, which increases their growth rates. However, removing white suckers does not significantly increase the population of yellow perch. (Becker, 1983; Hayes, 1990)

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

Do they cause problems?

White suckers feed on fish eggs; however, it does not seem to have a negative impact on the populations of other fish. (Becker, 1983)

How do they interact with us?

White suckers could be a valuable sport fish, although they are not caught as often as some other species. These fish are caught by commercial fisheries as food for both humans and animals, including pets. White suckers are also farmed in ponds. The most important economic value of white suckers is in their use as food or bait. The bait industry for white suckers was valued at $300,000 in Wisconsin in 1968. White suckers have sweet, white flesh, although it is not as firm as some other sport fish. Likewise, white suckers contain large bones between their muscle segments that can make them difficult to prepare, but they can be smoked, filleted, or ground into patties. (Becker, 1983; "White Sucker, Catostomus commersonii (pictured) Longnose Sucker, Catostomus catostomus", 2013)

  • Ways that people benefit from these animals:
  • food

Are they endangered?

White suckers are a very common and wide-ranging species with large population sizes and are considered a species of least concern. (Becker, 1983)


Aldo Hernandez (author), University of Michigan-Ann Arbor, Jeff Schaeffer (editor), University of Michigan-Ann Arbor, Leila Siciliano Martina (editor), Animal Diversity Web Staff.


NatureServe. 2013. "Catostomus commersonii" (On-line). Accessed October 20, 2013 at

Minnesota Department of Natural Resources. 2013. "White Sucker Catostomus commersonii" (On-line). Accessed October 20, 2013 at

State of Michigan. 2013. "White Sucker, Catostomus commersonii (pictured) Longnose Sucker, Catostomus catostomus" (On-line). Accessed October 21, 2013 at,4570,7-153-10364_18958-45693--,00.html.

Becker, G. 1983. Fishes of Wisconsin. Madison, Wisconsin: University of Wisconsin Press. Accessed October 21, 2013 at

Hayes, D. 1990. Competition between white sucker (Catostomus commersonii) and yellow perch (Perca flavescens) : Results of a whole-lake manipulation. Lansing, Michigan: Michigan Dept. of Natural Resources, Fisheries Division.

Long, W., W. Ballard. 1976. Normal Embryonic Stages of the White Sucker, Catostomus commersonii. Copeia, 2: 342-351.

McElman, J., E. Balon. 1980. Early ontogeny of the white sucker, Catostomus commersonii, with steps of saltatory development. Environmental Biology of Fishes, 5: 191-224.

Page, L., B. Burr. 2011. Peterson field guide to freshwater fishes of North America north of Mexico. Boston: Houghton Mifflin Harcourt.

Saint-Jacques, N., H. Harvey, D. Jackson. 2000. Selective foraging in the white sucker (Catostomus commersonii). Canadian Journal of Zoology, 78: 1320-1331.

Zimmerman, B. 2012. Stream Fishes of Ohio. Ohio: Ohio Department of Natural Resources.

University of Michigan Museum of ZoologyNational Science Foundation

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Hernandez, A. 2014. "Catostomus commersonii" (On-line), Animal Diversity Web. Accessed December 05, 2023 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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