Longnose sucker (Catostomus catostomus)

Longnose sucker

Top facts

  • The longnose sucker has the greatest state-wide distribution of any sucker species in the United States.
  • The longnose sucker can be differentiated from another Catostomus species, the white sucker, by its scales which are much finer.
  • The hearing organ of the longnose sucker is connected to the swim bladder, which helps to sense sound and vibrations.
  • Interestingly, the teeth of the longnose sucker are found within the throat rather than the mouth.
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Longnose sucker fact file

Longnose sucker description

GenusCatostomus (1)

The longnose sucker (Catostomus catostomus) is a long, cylindrically shaped fish with a single dorsal fin. The adult is reddish-brown, dark green or black from above with a paler underside. The juvenile of this species is usually dark grey and the body is patterned with small black spots. During the breeding season, the male has a brilliant reddish stripe along each side of its body and may develop tubercles for this period. The breeding female longnose sucker also has red stripes along the sides of its body, but they are much less distinct than in the male (3) (4) (5). The caudal fin of both sexes is forked with rounded lobes (3).

The mouth of the longnose sucker is downward-facing, allowing it to feed easily on the bed of rivers or lakes. The mouth is lined with small fleshy projections which allow the fish to create suction to pull prey items into its mouth (3). Interestingly, there are no teeth located on the jaws, and instead this fish has teeth further along the digestive tract to process food after it has been swallowed (3).

Also known as
black sucker, finescale sucker.
Catostomus aurora, Catostomus griseus, Catostomus nanomyzon.
Length: 38 - 63 cm (2)

Longnose sucker biology

The longnose sucker forages for invertebrates around the bottom of rivers or lakes (4), and its main prey items include insects, molluscs and crustaceans as well as algae and fish eggs. The downwards-facing mouth and large lips of this species allow it to suck up its prey with ease (3). The longnose sucker is prey for larger fish, such as the northern pike (Esox lucius), bass (Micropterus species), walleye (Sander vitreus) and burbot (Lota lota), as well as certain mammal species and fish-eating birds (2).

The longnose sucker lives for up to 20 years, and spawns multiple times throughout its life (6). Spawning generally occurs between May and July, although this is dependent on the water temperature. This fish species migrates upstream into shallow areas with a gravelly substrate to spawn (6). The male longnose sucker reaches sexual maturity at around four years of age, and the female can reproduce after around five years (5).

The male longnose sucker positions itself above the female and stays in place by grasping the female with its pelvic fins. The female then vibrates its body and releases eggs, while the male fertilises them. The female can produce up to 60,000 eggs which fall into crevices within the substrate (3). The eggs are yellowish in colour and usually take around two weeks to hatch, depending on the water temperature (3).


Longnose sucker range

The longnose sucker is common throughout most of Canada and Alaska, and can also be found in other areas of the United States such as the Delaware River in New York, the Monongahela River in Maryland and West Virginia and the Missouri River in Nebraska and Colorado. This species is also found in the Arctic basin of Siberia in Russia (4) (5).


Longnose sucker habitat

The longnose sucker is found in the clear, cold, deep water of lakes and tributary streams and is occasionally found in brackish water in the Arctic (4) (5).


Longnose sucker status

The longnose sucker has not yet been assessed by the IUCN.


Longnose sucker threats

The longnose sucker relies on clean, well-oxygenated gravel for correct egg development, which may be altered when the habitat is modified, particularly through erosion, sedimentation, flow alteration, and increased water temperature (6). The construction of dams may interrupt this species’ migration routes to spawning sites and prevent reproduction from occurring (6). The longnose sucker feeds largely on aquatic insects, which is likely to increase sensitivity to water pollution because many insects cannot tolerate even moderate water pollution (7). In Pennsylvania, the longnose sucker population has declined due to severe acidification of its habitat which has been caused by mine drainage (7).


Longnose sucker conservation

There are not known to be any conservation measures currently in place for the longnose sucker, although it is classified as critically imperilled in Pennsylvania (7). In 2007, a petition to provide the population of this species in the Monongahela River with endangered species protection was rejected. Although this population was thought to represent an ecologically and scientifically distinct group, the lack of scientific evidence meant that the population did not receive any legal protection (8).


Find out more

Find out more about the longnose sucker:

  • Page, L.M. and Burr, B.M. (1991) A Field Guide to Freshwater Fishes of North America North of Mexico. Houghton Mifflin Company, Boston, Massachusetts.

Find out about more species found in Illinois:



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Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
Slightly salty water, usually a mixture of salt and freshwater, such as that found in estuaries.
Caudal fin
The tail fin of a fish.
Diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
Dorsal fin
The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans (whales, dolphins and porpoises).
The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
A diverse group of invertebrates, mainly marine, that have one or all of the following: a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
Pelvic fins
In fish, the pair of fins found on the underside of the body.
The production or depositing of eggs in water.
A small, rounded, wart-like bump on the skin or on a bone.


  1. Catalogue of Life (May, 2014)
  2. Michigan Department of Natural Resources - White sucker and longnose sucker (April, 2014)
  3. Alaska Department of Fish and Game - Longnose sucker (April, 2014)
  4. Fishbase - Catostomus catostomus (April, 2014)
  5. Montana’s Official State Website Field Guide - Longnose sucker (April, 2014)
  6. Massachusetts Division of Fisheries and Wildlife: Natural Heritage and Endangered Species Programme - Longnose sucker (April, 2014)
  7. Pennsylvania Natural Heritage Programme - Longnose sucker (April, 2014)
  8. The Federal Register - March 8, 2007 (Volume 72, Number 45) (April, 2014)

Image credit

Longnose sucker  
Longnose sucker

© Konrad P. Schmidt

Konrad P. Schmidt


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