Becker, George C. / Fishes of Wisconsin
Minnow and carp family - cyprinidae, pp. 415-605 ff. PDF (93.4 MB)
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.
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