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Ictiobus cyprinellus

What do they look like?

Bigmouth buffalo are the largest members of the "sucker" family. They received their name due to their mouth, which has large, wide lips, with the upper lip almost level with the eyes. These fish have robust, elliptical bodies. Unlike smallmouth buffalo, bigmouth buffalo do not have an arched or ridge-like back. Bigmouth buffalo have fin rays, anal fin rays, pelvic fin rays, and a sickle-shaped dorsal fin that goes from midway down their backs to their tail. They can be a range of different colors, from bronze to a dark olive brown, with lighter shades on their sides and belly. Their first four vertebrate are modified to connect their swim bladder to their auditory system. Bigmouth buffalo have a single row of short, weak teeth and thin, fragile jaw arches. (Becker, 1983; Kleinholz, 2000; Walburg and Nelson, 1966)

  • Range mass
    36 (high) kg
    79.30 (high) lb
  • Average mass
    1.5 - 5.5 kg
  • Range length
    23 to 635 mm
    0.91 to 25.00 in
  • Average length
    430 - 529 mm

Where do they live?

Bigmouth buffalo (Ictiobus cyprinellus) are native to much of North America. Within Canada, their range extends from Manitoba to Saskatchewan. In the United States, they are found from Montana to Ohio, south to Alabama, and west to Texas. This species is now invasive in the Great Lakes region, which most likely resulted from bigmouth buffalo movement through the Wisconsin-Fox Canal to the Lake Michigan drainage. These fish are also non-native to reservoirs in Arizona, North Dakota, and Montana, as well as in aqueduct systems in southern California, where escape from fish hatcheries has allowed them to expand their range. (Edwards, 1983; Fuller, 2012; Kleinholz, 2000)

What kind of habitat do they need?

Bigmouth buffalo can live in many different freshwater habitats. Most often, they are found in slow moving channels or oxbows in rivers, where spring floods provide spawning habitat. However, bigmouth buffalo can also survive in inland lakes and reservoirs. During the summer, this species migrates into warm, shallow bays of the upstream portion of reservoirs, and look for deeper water in the fall and winter. Bigmouth buffalo are mostly a deep water species, although they can be found in different water depths. This species can tolerate areas with low oxygen, high water temperatures, and cloudy waters. They prefer areas with a low water current, but they can withstand high currents for short periods of time. (Becker, 1983; Edwards, 1983; Kleinholz, 2000; Walburg and Nelson, 1966)

  • Average depth
    below 20 m

How do they grow?

Bigmouth buffalo eggs are about 1.5 mm in diameter and are released throughout the months of April and June. The eggs are less likely to survive in extremely cloudy waters, or in areas with dramatic changes in water level. The eggs are openly released into the water before adhering to nearby vegetation or floating objects. Once the eggs are released, they incubate for 8 to 14 days without any parental care. Hatching occurs at about 17°C. Young bigmouth buffalo tend to gather in shallow bays, feeding on animal and plant forms of plankton. The young fish grow very quickly, toward the beginning of their first fall; the juveniles reach about 102 to 152 mm. However, in following years, their growth rate declines with age. (Becker, 1983; McClane, 1978; Walburg and Nelson, 1966)

How do they reproduce?

During spawning periods, males develop temporary breeding tubercles, or skin bumps, over the majority of their body. This makes it very easy to tell the males from the females. Females do not have tubercles, but have a thicker body. Bigmouth buffalo are group spawners. One breeding area can have 3 to 30 spawning units that reproduce at the same time, with 3 to 5 fish per unit. These spawning units often include one female, which is the center of the spawning unit, and 2 to 4 males. When the female is prepared to deposit her eggs, she sinks to the bottom. The males of her unit surround her, pushing the female upwards to the water surface. These males create a large rush and release reproductive milt. At the same time, females create large, rushing wakes at the water surface, combined with large, loud splashes from thrashing their tails. This mixes female eggs and male milt together. The resulting fertilized eggs are free to float in the water, before attaching to floating plants. (Becker, 1983; Kleinholz, 2000; Walburg and Nelson, 1966)

Spawning begins during spring flooding, usually after a series of warm calm nights. Spawning usually begins in water temperatures between 18 and 24°C, when night temperatures rarely drop below 12.8°C. If these conditions are not available, these fish may wait until they have better conditions for spawning. When the conditions are good, these fish migrate upstream to shallow coastlines near bays with dense vegetation. They prefer flooded marshes with clean, clear water. The breeding period is short; adults usually stay on the spawning ground for about a day. Hours after spawning, the fish return from the spawning floodplains to their native channels, completing a return journey of about 0.8 to 1.6 kilometers. (Becker, 1983; Edwards, 1983; Kleinholz, 2000; McClane, 1978; Walburg and Nelson, 1966)

  • How often does reproduction occur?
    Bigmouth buffalo reproduce once a year.
  • Breeding season
    These fish spawn from April to June.
  • Range time to hatching
    8 to 14 days
  • Average time to hatching
    10 days
  • Average time to independence
    Immediately minutes
  • Range age at sexual or reproductive maturity (female)
    2 to 9 years
  • Average age at sexual or reproductive maturity (female)
    3 years
  • Range age at sexual or reproductive maturity (male)
    1 to 8 years
  • Average age at sexual or reproductive maturity (male)
    3 years

Females produce about 100,000 eggs per pound of body weight. Parent fishes do not make nest sites or give any parental care. (Kleinholz, 2000; Walburg and Nelson, 1966)

  • Parental Investment
  • no parental involvement

How long do they live?

Bigmouth buffalo living in Canada usually live longer due to the shorter growing seasons. Females usually mature at lengths greater than 475 mm, while males mature at lengths of about 356 mm. The oldest known wild individual survived to be 20 years, however, the average wild lifespan is about 3 years. Individuals housed in captivity generally live 6 to 8 years. (Becker, 1983; Walburg and Nelson, 1966)

  • Range lifespan
    Status: wild
    20 (high) years
  • Average lifespan
    Status: wild
    6 years
  • Average lifespan
    Status: wild
    3 years
  • Typical lifespan
    Status: captivity
    6 to 8 years

How do they behave?

Throughout most of their lives, bigmouth buffalo commonly school near the middle of the water column or along the bottom of larger slow-moving rivers. (McClane, 1978)

Home Range

These fish make spawning journeys of 0.8 to 1.6 km from their native mainstream channels to the spawning floodplains. (Becker, 1983; Edwards, 1983; Kleinholz, 2000; McClane, 1978; Walburg and Nelson, 1966)

How do they communicate with each other?

Bigmouth buffalo seek food by using their senses of touch, taste, and sight. (Becker, 1983)

What do they eat?

Zooplankton are the most important food source within the diet of bigmouth buffalo. However, they may also eat small crustaceans, insect larvae, phytoplankton, and detritus. These fish may also be able to survive on periphyton, which is a mixture of algae, microbes, and detritus attached to sediment. They are known as an 'effective vacuum cleaner', getting much of their food from benthic rocks, plants, and the water itself. Their diet does not change with water depth, age, or size. (Becker, 1983; Kleinholz, 2000; Walburg and Nelson, 1966)

What eats them and how do they avoid being eaten?

Because their young grow so quickly and their adults are very large, bigmouth buffalo have very few predators. However, small bigmouth buffalo may be preyed on by larger sport fish. (Becker, 1983)

What roles do they have in the ecosystem?

By eating a wide variety of crustaceans, insects, and zooplankton bigmouth buffalo help control the lower levels of the aquatic food chain. Their ability to digest algae and detritus also helps decomposition and nutrient cycling in their ecosystems. (Becker, 1983; Kleinholz, 2000)

Do they cause problems?

Although they can be a tasty game fish, suckers are often seen as "trash fish" or "rough fish". In the overall public view, bigmouth buffalo lack value, taste, and importance as a game fish. (Kleinholz, 2000)

How do they interact with us?

In the lower Mississippi River Basin, bigmouth buffalo are a popular food fish, providing the basis for a large commercial fishery. These fish are high in protein, low in cholesterol, and their meat can be refrigerated for long periods of time. Bigmouth buffalo can also be a good addition to fisheries, as plankton and detritus feeders, they require little outside feeding in heavily used ponds. Furthermore, once hooked, bigmouth buffalo put up a dazzling fight, which may make them a good sport fish. Supporters of bigmouth buffalo in Wisconsin have claimed the species is "the musky of the southern Wisconsin streams, the sportiest, wariest, most mysterious and most sought-after native fish that swims, and, when smoked, a supreme gourmet’s delight”. Angling these fish using rods and reels is rarely successful. However, some anglers have succeeded in catching bigmouth buffalo using small hooks hidden in dough balls, near the water bottom. In addition, bows and arrows, crossbows, snares, gigs, spears, and spear guns may also help catch bigmouth buffalo. ("Bigmouth Buffalo Fishing in Arizona", 2009; Becker, 1983; Kleinholz, 2000)

  • Ways that people benefit from these animals:
  • food

Are they endangered?

Bigmouth buffalo populations are healthy and secure. They are not listed as threatened in any of their native or introduced regions. (Becker, 1983; Edwards, 1983)


Couryn Beleck (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.


2009. "Bigmouth Buffalo Fishing in Arizona" (On-line). Arizona Game and Fish Department. Accessed November 27, 2013 at

Becker, G. 1983. Fishes of Wisconsin. Madison: University of Wisconsin Press. Accessed September 24, 2013 at

Edwards, E. 1983. Habitat suitability index models : bigmouth buffalo. Washington, D.C.: Western Energy and Land Use Team, Division of Biological Service [sic], Research and Development, Fish and Wildlife Service, U.S. Dept. of the Interior.

Fuller, P. 2012. "USGS" (On-line). Ictiobus cyprinellus. Accessed December 15, 2013 at

Kleinholz, C. 2000. Species Profile Bigmouth Buffalo. Southern Regional Aquaculture Center, 723: 1-4. Accessed October 21, 2013 at

McClane, A. 1978. McClane's Field Guide to Freshwater Fishes of North America. New York: Holt, Rinehart and Winston.

Walburg, C., W. Nelson. 1966. Carp, river carpsucker, smallmouth buffalo, and bigmouth buffalo in Lewis and Clark Lake, Missouri River. Washington: Bureau of Sport Fisheries and Wildlife.

University of Michigan Museum of ZoologyNational Science Foundation

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Beleck, C. 2014. "Ictiobus cyprinellus" (On-line), Animal Diversity Web. Accessed May 24, 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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