Page 600

600    Minnow and Carp Family-Cyprinidae 
Fathead Minnow 
Pimephales promelas Rafinesque. Pimephales-fat, head; 
     promelas-in front, black. 
Other common names: northern fathead minnow, 
     blackhead minnow, Tuffy minnow, fathead. 
Male (tuberculate) 85 mm, Tomorrow R. (Portage Co.), 2 July 
1958 
Female 65 mm, Tomorrow R. (Portage Co.), 2 July 1958 
DESCRIPTION 
Body short, stout, slightly compressed laterally, often 
with a fat belly Average length 51 mm (2 in). TL = 
1.22 SL. Depth into TL 3.6-5.0. Head length into TL 
4.0-4.9; top of head and back behind head slightly 
flattened. Snout blunt, extending slightly beyond up- 
per lip. Mouth small, almost terminal, strongly 
oblique to almost vertical; mouth extending to below 
anterior nostril; barbel absent. Pharyngeal teeth 4-4; 
teeth slender, scarcely hooked, with elongate cutting 
surfaces. Eye into head length 3.3-5.4. Gill rakers 
short, pointed, flattened (like tip of leaf), 12-14. Dor- 
sal fin origin over, to slightly in advance of, origin of 
pelvic fin; dorsal fin rays 8 (short ray at front of dorsal 
fin not tightly bound to first principal ray, as is the 
case in most minnows); anal fin rays 7; pectoral fin 
rays 15-16; pelvic fin rays 8. Lateral series scales 
43-49; lateral line short, incomplete. Scales on back 
before dorsal fin, small and crowded. Digestive tract 
long, 1.4-1.7 TL. Chromosomes 2n = 50 (Gravell 
and Malsberger 1965). 
   Alimentary tract of the fathead minnow, diagrammatic 
   Back and sides to lateral stripe dark olive; below 
lateral stripe, whitish with black peritoneum show- 
ing through belly. Lateral stripe, extending from cau- 
dal peduncle to head, faint to distinct in young, in 
nonbreeding adults, and in breeding females; in 
breeding males stripe is absent, or, if present, diffuse 
anteriorly. Basicaudal spot small to absent. Males 
with a black blotch on lower third of first 2 or 3 rays. 
Scale pockets above lateral stripe distinctly edged in 
pigment; scale pockets below stripe, only faintly pig- 
mented. Peritoneum black. 
  Breeding male black on head; rest of body, includ- 
ing fins, dark. Breeding tubercles in 3 main rows on 
snout, several tubercles on lower jaw, scattered mi- 
nute tubercles on top of head. Fleshy gray pad of 
"skin" extending from nape to dorsal fin. Breeding 
female with distended belly. 
  Sexual dimorphism: A protruding urogenital struc- 
ture (ovipositor) evident in female at least 1 month 
prior to spawning; absent in male (Flickinger 1969). 
  Hybrids: Fathead minnow x bluntnose minnow 
(Trautman 1957). 
SYSTEMATIC NOTES 
The subspecies ascribed to Wisconsin is the northern 
fathead minnow, Pimephales promelas promelas Rafin- 
esque (Hubbs and Lagler 1964). The apparent sub- 
specific differences between the northern (north cen- 
tral United States) and southern (Texas and Oklahoma) 
forms were examined by Taylor (1954), who found 
that the characters used for separating the forms are 
highly variable and not conclusive.