Semotilus atromaculatus
Creek Chub

Creek Chub

Flora, fauna, earth, and sky...
The natural history of the northwoods



  • Semotilus, from the Greek, sema, "banner", referring to the dorsal fin; and the second part meant to mean "spotted"
  • atromaculatus, from the Latin, "black spot"
  • Common name from its preferred habitat
  • Other common names include: Blackspot Chub, Brook Chub, Common Chub, Horned Dace ( from breeding tubercles), Mud Chub, Northern Creek Chub, Silvery Chub, Tommycod, Mulet à cornes


  • Kingdom Animalia
    • Phylum Chordata, animals with a spinal chord
    • Subphylum Vertebrata, animals with a backbone
      • Superclass Osteichthyes, bony fishes
      • Class Actinopterygii, ray-finned and spiny rayed fishes
      • Subclass Neopterygii
      • Infraclass Teleostei
        • Superorder Ostariophysi
        • Order Cypriniformes, minnows and suckers
        • Family Cyprinidae, carps and minnows
          • Genus Semotilus, the creek chubs


  • A larger minnow of smaller streams
  • Length to 8"-10"
  • Coloration
    • black or bluish, olive to purplish above
    • silvery below
    • lateral stripe from tip of snout to base of tail fin
    • can appear striped because of the dark color above, light streak just above the dark lateral line, and then white beneath.
    • wedge-shaped spot at base of tail
    • dark spot in first 3 rays at the base of dorsal fin
    • fins may become light yellowish to light olive in color
    • intensity of the lateral stripe and dorsal color dependent upon water clarity, darker individuals coming from clearer waters
  • Body
    • stout and robust
    • dorsal fin set behind the base of the pelvic fins
    • anal fins of 8 rays
    • pectoral fins of 16/17 rays
    • pelvic fins of 8 rays
    • body scales very small, appearing cross-hatched on upper back and sides.
    • lateral line scales from 49 to 64 in number, sometimes interrupted by missing pores
  • Head
    • broad and blunt
    • very large mouth, slightly oblique, extends to below the eye
    • small, flap-like barbel in groove in middle of upper jaw
    • single, small barbel in the corner of each jaw, sometimes hidden between the maxillary and premaxillary
    • hooked pharyngeal teeth, on stout arches, in two rows, with a 2, 5-4, 2 pattern.
  • Lifespan
  • During spring spawning season, males take on a bright, rosy coloration and develop at least four large tubercles on each side of their heads.


  • Distinguished from other minnows by
    • a black spot in the first 3 rays of the dorsal fin
    • a very large mouth
    • a small, flap-like barbel in the groove in the middle of the upper jaw
    • a wedged-shaped spot at the base of the tail
  • Adults are most easily identified by the dark spot at the base of the dorsal fin.


  • Most of eastern US and southeastern Canada in Atlantic, Great Lakes, Hudson Bay, Mississippi, and Gulf basins as far west as Manitoba, eastern Montana, Wyoming, Colorado, eastern Oklahoma, and eastern Texas.


  • Small to medium-sized streams with silt-free gravel bars.
  • Will endure turbidity provided the current sweeps the gravel free of silt.


  • Primarily aquatic and terrestrial insects, insect larvae, crustaceans, mollusks, and small fishes, along with incidental ingestion of algae and other minute plants.
  • An important forage fish for larger predacious sport fish and a competitor with them for aquatic insect and crustaceans.



  • Small creek chubs are often used as bait, because they are hardy, abundant, and easily kept in confinement.
  • Provide some angling in small streams, particularly for the young fishermen, and are an excellent food fish.


  • Spawning activity commences in May when the water temperature reaches about 65º F.
  • Males prepare a nest by mounding up gravel about 3" high and several feet in length using the snout and mouth.
  • Eggs are deposited in the nest by one or more females over a period of 2 weeks and covered with gravel by the male as nest building continues. The male guards the nest against intruders with tubercle displays or swimming in a ritualized combative posture.
  • Attains full size after 4 years of life.



Boreal border

Last updated on 15 October 1999