Cycleptus elongatus 

blue sucker



Type Locality

Ohio River (Lesueur 1817).


Etymology/Derivation of Scientific Name

Cycleptus – round and slender, apparently meant to mean “small round mouth” by the author of the name, C.S. Rafinesque; elongatus – elongate, in reference to general body shape (Burr and Mayden 1999).



Catostomus elongatus Lesueur 1817:103.

Cycleptus nigrescens

Sclerognathus elongatus

Cycleptus elongatus Hubbs 1957:100; Hubbs et al. 1991:24, 2008:26.



Maximum size: 825 mm SL (Burr and Mayden 1999).


Coloration: Life colors of male olive blue or slate olive on dorsum and sides of body with brassy reflections; venter bluish-white; lips white; all fins dark blue-gray, dusky, or black. Breeding males darken to blue-black. No significant color differences between males and females. Peritoneum silvery (Burr and Mayden 1999).


Teeth count: 40-45 teeth per bone; teeth relatively large, arranged in comblike fashion (Eastman 1977; Burr and Mayden 1999).


Counts: 50+ lateral line scales; 22-30 dorsal fin rays (Hubbs et al. 1991, 2008). Burr and Mayden (1999) listed the following counts for specimens from the Red River drainage: 56 (54-58) lateral-line scales, 31 (27-34) dorsal fin rays; the following are counts listed for specimens from the Sabine-Neches River drainage: 55 (54-60) lateral-line scales, 28 (24-31) dorsal fin rays; the following counts were listed for specimens from the Colorado River drainage: 54 (53-55) lateral-line scales, 31 (29-32) dorsal fin rays.


Body shape: Terete; extremely muscular and heavy-bodied (Moss et al. 1983). Elongate body, oval in cross section (Burr and Mayden 1999). Eye closer to back of head than to tip of snout; head abruptly more slender than body, in adults; dorsal fin base more than one-third of standard length (Hubbs et al. 2008).


Mouth position: Inferior (Miller and Robison 2004).


External morphology: Lip papillae short, only around mouth (Hubbs et al. 2008). Pelvic fins large; pectoral fins large and falcate; lateral line well developed; snout acute; eye small (Cross 1967). Anal fin in adults small, generally straight-edged, sometimes falcate. Caudal fin in adults large, widely forked, lobe tips slightly rounded to pointed, inner margins straight; both lobes about equal in length. Upper lobe more pointed and longer in young, juveniles, and some adults (Burr and Mayden 1999). Breeding males and females with small tubercles covering body and fins; in breeding males, tubercles prominent and enlarged on snout, around eyes and on opercle (Moss et al. 1983).


Distribution (Native and Introduced)

U.S. distribution: Found in large rivers throughout the Mississippi Basin continuing southward into Texas (Hubbs et al. 2008).


Texas distribution: Occurs in limited numbers through the major streams of the state, except the Rio Grande (Hubbs et al. 2008). Warren et al. (2000) list the following drainage units for distribution of Cycleptus elongatus in the state: Red River (from the mouth upstream to and including the Kiamichi River), Sabine Lake (including minor coastal drainages west to Galveston Bay), Galveston Bay (including minor coastal drainages west to mouth of Brazos River), Brazos River, Colorado River, San Antonio Bay (including minor coastal drainages west of mouth of Colorado River to mouth of Nueces River), Nueces River.


Abundance/Conservation status (Federal, State, NGO)

State Threatened in Texas (Hubbs et al. 2008). Populations in the southern United States are vulnerable (Warren et al. 2000). Williams et al. (1989) listed status as Special Concern.


Habitat Associations

Macrohabitat: Throughout range, inhabits large, deep rivers, and deeper zones of lakes (reservoirs; Cross 1967). In the lower Mississippi River, species was abundant in main channel, reveted bank habitats; common in natural steep bank and lotic habitats; found regularly, but in low numbers in pools (Baker et al. 1991). Species rarely collected in the main body of Lake Texoma, Oklahoma and Texas, usually taken in the spring at all depths down to 15 feet; slightly more common in the tailwaters (Riggs and Bonn 1959).


Mesohabitat: Found over cobble and/or bedrock substrates; adults occupy deep riffles (typically 1-2 m depth) in areas of very swift flow, with current speeds from 100-260 cm/s; juveniles occupy shallower, less swift water (Moss et al. 1983); in laboratory stream channels, movement of juveniles was encumbered over irregular substrates in slower current. Cross (1967) collected fish from the Neosho River, Kansas, in strong currents over bottoms of exposed bedrock or rubble and gravel; juveniles found in broader less turbulent riffles. In areas of the Missouri River channelized by dikes, this species was most abundant in fast water at the tips of rock dikes and at low spots within a dike (Robinson 1977). Morey and Berry (2003) reported that sub-adults and adults were seasonally abundant in the lower main stem of two Missouri River tributaries near riffles and rock dams; adults tended to be associated with swift flows. In the Mississippi River, shallow, slack waters associated with islands (island borders and island sloughs) were important nursery areas for young fish (Adams et al. 2006).



Spawning season: Moss et al. (1983) reported spawning in May in the Neosho River, Kansas, at water temperatures of

20-23°C. In Kansas, Cross (1967) reported collection of individuals in breeding condition in April, at water temperatures of 50-60°F. In a study of a Mississippi River population, male characteristics indicated a late April-early May spawning season (Rupprecht and Jahn 1980). In the Mississippi River, spawning occurred over a 10-28 day period during the spring, and corresponded with rising water temperatures of 14-18°C during mid-late April – early-mid May (Adams et al. 2006). Females with freely-flowing roe collected in late April when water temperature measured 16.5°C


Spawning habitat: In deep riffles (1-2 m) with cobble and bedrock substrates; water velocities at spawning sites were

1.8 m/sec. (Moss et al. 1983). In the Wabash River near Lafayette, Indiana, ripe specimens were captured in shallow water (0.3-3 m depth) over sand, gravel, and cobble substrates (Daugherty et al. 2008). In the Grand River, Missouri, spawning aggregation found in fastest water available  that was breaking over large cobbles and boulders (variable velocity, pockets of direct flow greater than 1.0 m/s), and was between 0.5 and 1.0 m deep (Vokoun et al. 2003).


Reproductive strategy:


Fecundity: Mean absolute fecundity of females was 150,704 (range 26,829-267,471) in the Wabash River, Indiana; mean estimated egg size was 278 eggs g־¹ (range 229-364 eggs g־¹; Daugherty et al. 2008). Females age 6 (85 mm TL) produced 76,227 ova, and those of age 8 (680 mm TL) produced 149,520 ova indicating egg number is closely related to length of individual; largest eggs from non-breeding gravid females collected in August averaged about 1.0 mm in diameter (Rupprecht and Jahn 1980). Moss et al. (1983) reported that eggs are opaque, slightly yellow, adhesive and average 2.2 mm in diameter.


Age at maturation: Daugherty et al. (2008) estimated size-at maturity for specimens from Wabash River, Indiana, at 515 mm TL for males and 568 mm TL for females. Moss et al. (1983) collected a 507 mm TL, 1.02 kg, age III sexually mature specimen from the Neosho River, Kansas. In the Grand River, Missouri, minimum total lengths of mature specimens was 444 mm TL for one male specimen (all other males collected were greater than 583 mm TL), and 631 mm TL for females; sexually mature fish captured ranged in age from 9-22 years (Vokoun et al. 2003). According to Rupprecht and

Jahn (1980), of those fish collected from Pool 20 of the Mississippi River, the males generally reached sexual maturity at age IV (youngest specimen measured 503 mm TL), and the females at age VI (youngest specimen measured 573 mm TL).


Migration: Adults probably winter in deep pools and move upstream in spring to spawn in riffles (Cross 1967). Males migrate into spawning area before females (Moss et al. 1983).


Longevity: 22 years of age reported from the Grand River, Missouri (Vokoun et al. 2003).16 years of age reported from the Kansas River, Kansas (Eitzmann et al. 2007). 11 years of age reported from the upper Yazoo River basin, Mississippi (Hand and Jackson 2003). 10 years of age (possibly 13 years) reported form Pool 20, Mississippi River (Rupprecht and Jahn 1980).


Food habits: Fish collected from Pool 20 of the Mississippi River primarily consumed Tricoptera and Diptera larvae and pupae, and lesser numbers of Ephemeroptera larvae and amphipods (Rupprecht and Jahn 1980). Populations in the Neosho River, Kansas, reported to feed on hellgrammites (Corydalus), caddisflies (Hydropsyche and Cheumatopsyche), fingernail clams (Sphaerium), filamentous algae (mainly Cladophora) and leaf litter; young fish feed on smaller insect larvae (dipterans and caddisflies; Moss et al. 1983). In the Mississippi River, young fish used diverse feeding modes in the shoreline areas, consuming benthic (Chironomidae larvae), nektonic (Cyclopoida and Cladocera) and neustonic (Chironomidae adults, Bryozoa statoblasts and Thripidae) forms; young fish were observed picking at items floating on water surface, and skimming surfaces of floating logs and willow roots (Adams 2006). Fish inhabiting the tailwater habitat of Lewis and Clark Lake, Nebraska-South Dakota, consumed large amounts of algae from late-September to early-November when periphytic algae reached peak abundance; in spring months, primary diet items were chironomids and zooplankton (Walburg et al. 1971).


Growth and Population structure: Fish average 189-205 mm TL at the end of the first year, and are 296-346 mm, 397-461 mm, 471-512 mm, 533-569 mm, 578-611 mm, 589-641 mm, 643-680 mm, 711-732 mm, and 798 mm at ages 2-10, respectively (Walburg et al. 1971; Rupprecht and Jahn 1980; Moss et al. 1983). In Neosho River, Kansas, populations Moss et al. (1983) found that females were consistently larger than males at all ages; mature females reach greater maximum ages, weights and lengths (9 years, 4.1 kg, 763 mm TL) than males (7 years, 3.7 kg, 749 mm TL). Hand and Jackson (2003) reported calculated total length at annulus for fish collected in the upper Yazoo River basin, Mississippi: 159-203 mm TL at age 1, 231-395 mm TL at age 2, and 289-395 mm TL, 361-466 mm TL, 406-521 mm TL, 442-544 mm TL, 476-575 mm TL, 518-610 mm TL, 565-628 mm TL, 624-638 mm TL, and 661 mm TL for ages 3-11, respectively. Spawning aggregation in the Grand River, Missouri had a mean age of 15 years (fish ranged from 9-22 years based on scales); male to female ratio was 5.5:1; mean length for males was 659 mm TL and mean length was 721 mm TL for females; females were longer than males at age and no significant age-length relationship was evident (Vokoun et al. 2003); total length was 672 mm for a fish 9 years of age, and total length ranged from 625-693 mm for specimens 10 years of age, and 615-687 mm, 600-745 mm, 591-702 mm, 583-712 mm, 444-755 mm, 642-781 mm, 638-770 mm, 663-781 mm, 651-731 mm, 632-800 mm, 650 mm, and 745 mm for fish 11-22 years of age, respectively. In sampling of both the James River and the Big Sioux River (South Dakota), fish between 500-700 mm TL dominated length distributions (specimens ranged from 374-717 mm); ages ranged from 2-9 years, with 6-year-old fish collected most frequently; fish grew rapidly during juvenile stages (<age 5), but growth slowed afterward (Morey and Berry 2003).


Phylogeny and morphologically similar fishes

Hubbs et al. (2008) refers to the Rio Grande, Texas, Cycleptus population as the Rio Grande blue sucker, Cycleptus sp. (formerly referred to as Cycleptus elongatus; Hubbs et al. 1991). Based on phylogenetic analyses, Bessert (2006) stated that Cycleptus in the Rio Grande basin is monophyletic and clearly divergent from C. elongatus. Buth and Mayden (2001) proposed that the Rio Grande drainage population to be recognized as a different species, noting that this population required further analysis of morphological and molecular variation and a formal description. According to Burr and Mayden (1999), Cycleptus samples from the Rio Grande were found to be divergent in a few characters compared to samples from other parts of the range; also preliminary studies (by Donald G. Buth and R.L. Mayden) of enzyme products revealed fixed differences in isozymes and allozymes in samples of Cycleptus from the Rio Grande mainstem when compared to samples from other parts of the range (samples from Texas coastal rivers not examined).


Differences between C. elongatus and Cycleptus sp. include the following: in C. elongatus the lip papillae is short, only around the mouth, while in Cycleptus sp. the lip papillae is long, extending forwards onto end of snout; also, Cycleptus elongatus does not occur in the Rio Grande basin, while Cycleptus sp. is found only in the Rio Grande basin (Hubbs et al. 2008). Further, Burr and Mayden (1999) indicated that Cycleptus sp. appear more golden or brassy in overall body color than Cycleptus elongatus (except during spawning season); also adult and larger juvenile Cycleptus sp. sometimes have up to 12 (on largest adults) vague stripes on their side; Burr and Mayden (1999) found this variable feature in only the Colorado River drainage population of Cycleptus elongatus.


Cycleptus elongatus is unlikely to be confused with other catostomids, as the species differs from all other suckers in the high lateral scale count (greater than 49) and long dorsal fin (Ross 2001).


Total myomere counts for larval Cycleptus elongatus ranged from 47-54; larval fish ≥12.5 mm TL are coal black to dark gray in life; yolk was absorbed by 13 mm TL (Hogue et al. 1981); protolarvae (fish up to about 12 mm TL) with more than 46 myomeres, and depth of head at posterior margin of orbit more than 11% of total length; mesolarvae (>12 mm TL to about 15 mm TL) with more than 46 myomeres, depth of body at vent (including anus) more than 8.7% of total length, and heavily pigmented; metalarvae (<20 mm TL) with more than 46 total myomeres, and having melanophores scattered on lateral surfaces with no apparent pattern; metalarvae (≥20 mm TL) with lips papillose, long dorsal fin, and heavy pigmentation.


Host Records

Rhabdochona cascadilla (Nematoda : Thelazioidea) detected in the intestine of Cyclepus elongatus, from Illinois (Dyer and Poly 2002). Myzotryma cyclepti (Monogenea) and Anonchohaptor olseni (Monogenea) reported from C. elongatus in the Missouri River, North Dakota (Leiby et al. 1973) ; M. cyclepti also reported from this species in the Mississippi River, Illinois (Robinson and Jahn 1980). A single leech, Helobdella sp. found on a specimen from Big Bend Reservoir, Missouri River, South Dakota (Alleman 1965).


Commercial or Environmental Importance

Abundance of Cycleptus elongatus has been decreased by impoundment, pollution, and reduced water flows in those systems in which it occurs (Edwards et al. 2004). Williams et al. (1989) listed threats to this species: present or threatened destruction, modification, or curtailment of its habitat or range; and other natural or manmade factors affecting its continued existence (hybridization, introduction of exotic or transplanted species, predation, competition). Spawning migration may be blocked and spawning areas inundated by dams, contributing in part to the decline of this species (Cross 1967). Walburg et al. (1971) reported collection of numerous Cycleptus elongatus in tailwaters below dams, but almost none were present in the reservoir above.


[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Hubbs (1957); Branson (1962); Nature Conservancy (2004).]  



Adams, S.R., M.B. Flinn, B.M. Burr, M.R. Whiles, and J.E. Garvey. 2006. Ecology of larval blue sucker (Cycleptus elongatus) in the Mississippi River. Ecology of Freshwater Fish 15:291-300.

Alleman, G.A. 1965. Parasites of fishes of Oahe and Big Bend Reservoir, South Dakota. Master’s Thesis, South Dakota State University. 46 pp.

Baker, J. A., K. J. Kilgore, and R. L. Kasu. 1991. Aquatic habitats and fish communities in the lower Mississippi River. Rev. Aqat. Sci. 3(4):313-356.

Bessert, M.L. 2006. Molecular systematics and population structure in the North American endemic fish genus Cycleptus (Teleostei: Catostomidae). Ph.D. dissertation, University of Nebraska, Lincoln. 219 pp.

Branson, B.A. 1962. Comparative cephalic and appendicular osteology of the fish family Catostomidae. Part I, Cycleptus elongatus (Lesueur). The Southwestern Naturalist 7(2):81-153.

Burr, B.M., and R.L. Mayden. 1999. A new species of Cycleptus (Cypriniformes: Catostomidae) from Gulf Slope drainages of Alabama, Mississippi, and Louisiana, with a review of the distribution, biology, and conservation status of the genus. Bulletin of the Alabama Museum of Natural History 20:19-57.

Buth, D.G., and Mayden, R.L. 2001. Allozymic and isozymic evidence for polytypy in the North American catostomid genus Cycleptus. Copeia 2001:899-906.

Cross, F.B. 1967. Handbook of Fishes of Kansas. University of Kansas Museum of Natural History Misc. Publ. No. 45, Lawrence. 357 pp.

Daugherty, D.J., T.D. Bacula, and T.M. Sutton. 2008. Reproductive biology of blue sucker in a large Midwestern river. Journal of Applied Ichthyology 24(3):297-302.

Dyer, W.G., and W.J. Ploy. 2002. First record of Rhabdochona cascadilla Wigdor, 1918 (Nematoda: Thelazioidea) in the blue sucker, Cycleptus elongatus (Lesueur, 1817), from Illinois. Transactions of the Illinois Academy of Science 95(2):107-109.

Eastman, J.T. 1977. The pharyngeal bones and teeth of catostomid fishes. American Midland Naturalist 97(1):68-88.


Edwards, R.J., G.P. Garrett, and N.L. Allan. 2004. Aquifer-dependent fishes of the Edwards Plateau region. Chapter 13, pp. 253-268 in: Mace, R.E., E.S. Angle, and W.F. Mullican, III (eds.). Aquifers of the Edwards Plateau. Texas Water Development Board. 360 pp.

Eitzmann, J.L., A.S. Makinster, C.P. Paukert. 2007. Distribution and growth of blue sucker in a Great Plains river, USA. Fisheries Management and Ecology 14(4):255-262.

Hand, G.R., and D.C. Jackson. 2003. Blue sucker stock characteristics in the upper Yazoo River basin, Mississippi, USA. Fisheries Management and Ecology 10(3):147.

Hogue, J.J., Jr., J.V. Conner, and V.R. Kranz. 1981. Descriptions and methods for identifying larval blue sucker, Cycleptus elongatus (LeSueur). Rapp. P.-v. Reun. Cons. Int. Explor. Mer. 178:585-587.

Hubbs, C. 1957. Distributional patterns of Texas fresh-water fishes. The Southwestern Naturalist 2(2/3):89-104.

Hubbs, C., R. J. Edwards, G. P. Garrett. 1991. An annotated checklist of the fishes of Texas, with keys to identification of species. Texas Journal of Science, Supplement 43(4):1-56.


Hubbs, C., R.J. Edwards, and G.P. Garrett. 2008. An annotated checklist of the freshwater fishes of Texas, with keys to identification of species. Texas Journal of Science, Supplement, 2nd edition 43(4):1-87.

Leiby, P.D., D.C. Kritsky, and D.D. Bauman. 1973. Studies on helminthes of North Dakota. VII. Ancyrocephalinae (Monogenea) from the gills of the blue sucker, Cycleptus elongatus (LeSueur). Can. J. Zool. 51:777-779.

Lesueur, C. A. 1817. A new genus of fishes, of the order Abdominales, proposed, under the name of Catostomus; and the characters of this genus, with those of its species, indicated. J. Acad. Nat. Sci. Phil. 1(1):88-111.

Miller, R.J., and H.W. Robison. 2004. Fishes of Oklahoma. University of Oklahoma Press, Norman. 450 pp.

Morey, N.M., and C.R. Berry, Jr. 2003. Biological Characteristics of the blue sucker in the James River and the Big Sioux River, South Dakota. Journal of Freshwater Ecology 18(1):33-42.

Moss, R. E., J. W. Scanlan, and C. S. Anderson. 1983. Observations on the natural history of the blue sucker (Cycleptus elongatus Le Sueur) in the Neosho River. Amer. Midl. Nat. 109(1):15-22.


The Nature Conservancy. 2004. A biodiversity and conservation assessment of the Edwards Plateau ecoregion. Edwards Plateau Ecoregional Planning Team, The Nature Conservancy, San Antonio, Texas. 30 pp.

Riggs, C.D., and E.W. Bonn. 1959. An annotated list of the fishes of Lake Texoma, Oklahoma and Texas. The Southwestern Naturalist 4(4):157-168.

Robinson, G.L., and L.A. Jahn. 1980. Some observations of fish parasites in pool 20, Mississippi River. Trans. Am. Microsc. Soc. 99:206-212.

Robinson, J.W. 1977. The utilization of dikes by certain fishes in the Missouri River. Federal Aid Project No. 2-199-R, Missouri Department of Conservation, Jefferson City. 30 pp.

Ross, S. T. 2001. The Inland Fishes of Mississippi. University Press of Mississippi, Jackson. 624 pp.

Rupprecht, R. J. and L. A. Jahn. 1980. Biological notes on blue suckers in the Mississippi River. Trans. Amer. Fish. Soc. 109(3):323-326.

Vokoun, J.C., T.L. Guerrant, and C.F. Rabeni. 2003. Demographics and chronology of a spawning aggregation of blue sucker (Cycleptus elongatus) in the Grand River, Missouri, USA. Journal of Freshwater Ecology 18(4):567-575.

Walburg, C. H., G. L. Kaiser, and P. L. Hudson. 1971. Lewis and Clark Lake tailwater biota and some relations of the tailwater and reservoir fish populations, pp. 449-467. In; Reservoir fisheries and limnology. G. E. Hall, ed. Spec. Publ., no. 8, American Fisheries Society, Washington, D.C.

Warren, L. W., Jr., B. M. Burr, S. J. Walsh, H. L. Bart, Jr., R. C. Cashner, D. A. Etnier, B. J. Freeman, B. R. Kuhajda, R. L. Mayden, H. W. Robison, S. T. Ross, and W. C. Starnes. 2000. Diversity, Distribution, and Conservation status of the native freshwater fishes of the southern United States. Fisheries 25(10):7-29.


Williams, J.E., J.E. Johnson, D.A. Hendrickson, S. Contreras-Balderas, J.D. Williams, M. Navarro-Mendoza, D.E. McAllister, and J.E. Deacon. 1989. Fishes of North America Endangered, Threatened, or of Special Concern. Fisheries 14(6):2-20.