Bullhead Minnow
  • Side view adult.
  • Side view adult.
  • Side view adult.
  • Top view adult.
  • Bottom view adult.
  • Head-on view adult.
  • Close-up flank.
  • Close-up head.
  • Close-up mouth and snout.
  • Close-up tail.
  • Close-up dorsal fin.
  • Close-up anal fin.
  • Close-up pectoral fin.
  • Close-up pelvic fin.
  • The scales between the head and the dorsal fin are small and crowded, relative to the scales on the flanks.
  • The peritoneum is silvery, and the digestive tract is short.
  • Close-up anal fin: There are seven anal fin rays.
  • There are 40-45 lateral line scales and a thin lateral stripe with a caudal spot.
  • The snout is rounded/triangular; the mouth is terminal and oblique, extending to the front of the eye.
  • Dorso-lateral view of a breeding male: Notice the gray spongy tissue in the dorso-lateral area.
  • Close-up dorsal fin of a breeding male: The first ray of the dorsal fin is shortened and thickened and widely spaced from the second.
  • Side view of a breeding male: Breeding males develop dark coloration on their body and fins.
  • Side view of a breeding male: Breeding males develop dark coloration on their body and fins.
  • Head-on view of a breeding male: Notice the tubercles in the head area.
  • Close-up head of a breeding male: Notice the tubercles in the head area.
DescriptionSimilar Species
Family
Minnows (Cyprinidae)
Body
Mouth and snout: Mouth terminal to slightly subterminal and slightly oblique without any teeth. No barbels. Snout triangular to rounded. Body patterning, color, and scales: Light olive, brown, or tan, usually with a black lateral stripe, sometimes missing or faint, yielding a solid color on flanks, grading to white or cream on the belly. Dorsal fin usually with a dark pigment blotch on first 2-3 membranes. Often a spot at the base of the tail, sometimes not distinct from lateral stripe. Other fins without distinctive markings (but see Breeding Adults below). 40-45 cycloid lateral line scales, rounded in shape. Body shape and size: Body generally fusiform but also could be perceived as cylindrical (rigid body, round in cross section, with relatively little tapering from back of head to front of caudal peduncle). Back often slightly arched in front of dorsal fin. Typically 40-75 mm (1.5-3 in) TL; maximum from Wisconsin about 90 mm (3.5 in).
Fins
Tail, dorsal and other fins: Forked tail with rounded tips. Single dorsal fin with 8 rays and no spines. Pelvic fins abdominal. No adipose fin. Anal fin with 7 rays and no spines.
Distinguishing Characteristics
The bullhead minnow can be distinguished by its scales on back between head and dorsal fin (predorsal scales) being smaller, more numerous, and more crowded together than scales in a comparably sized area of the flank; 40-45 lateral line scales; 7 anal fin rays; slightly oblique and terminal to slightly subterminal mouth that extends to anterior of eye; triangular to rounded snout; peritoneum silvery and digestive tract 0.6-0.7 TL. See also similar species information.
Breeding Adults
Males – Dark body, almost black, especially the head. Tail, dorsal, and and 1st two pectoral fin rays outlined with dark pigment; anal and pelvic fins clear. Spot on dorsal fin especially conspicuous. 1st ray of dorsal fin thickened and shortened and widely spaced from 2nd ray. Obvious large tubercles on snout. Grayish “pad” of spongy tissue in dorso-lateral area behind head.
Juveniles
Similar to adults.
Hybrids
None confirmed from Wisconsin.
Compare Similar Species
Scales
Chub, CreekPredorsal scales small and crowded; 49-66 lateral line scales
Chub, HornyheadPredorsal scales similar to flank scales; 38-48 lateral line scales
Minnow, BluntnosePredorsal scales small and crowded; 40-44 lateral line scales
Minnow, BullheadPredorsal scales small and crowded; 40-45 lateral line scales
Minnow, FatheadPredorsal scales small and crowded; 43-49 lateral line scales
Minnow, OzarkPredorsal scales similar to flank scales; 36-38 lateral line scales
Anal Fin
Chub, Creek8 rays
Chub, Hornyhead7 rays
Minnow, Bluntnose7 rays
Minnow, Bullhead7 rays
Minnow, Fathead7 rays
Minnow, Ozark8 rays
Mouth and Snout
Chub, CreekMouth terminal, slightly oblique, extending to almost middle of eye; snout triangular
Chub, HornyheadMouth subterminal, slightly oblique, extending to front of eye; snout triangular
Minnow, BluntnoseMouth subterminal, nearly horizontal, extending to front of eye; snout blunt to rounded
Minnow, BullheadMouth terminal to slightly subterminal, slightly oblique, extending to front of eye; snout triangular to rounded
Minnow, FatheadMouth terminal or superior, oblique or nearly vertical, does not extend to eye; snout triangular to rounded
Minnow, OzarkMouth subterminal, slightly oblique, extending to front of eye; snout triangular
Digestive Tract
Chub, CreekShort tract, 0.6-0.7 total length; peritoneum silvery or gray
Chub, HornyheadRelatively long tract, ~0.9 total length; peritoneum dusky to brownish
Minnow, BluntnoseRelatively long tract, 1.0-1.2 total length; peritoneum black
Minnow, BullheadShort tract, 0.6-0.7 total length; peritoneum silvery
Minnow, FatheadLong tract, 1.4-1.7 total length; peritoneum black
Minnow, OzarkVery long tract, 1.9-2.4 total length; peritoneum black
Similarity Index
Chub, CreekModerately similar
Chub, HornyheadModerately similar
Minnow, BluntnoseVery similar
Minnow, BullheadN/A
Minnow, FatheadModerately similar
Minnow, OzarkModerately similar
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