Iowa DNR
River & Stream Biological Monitoring
Fish and Benthic Macroinvertebrate Surveys
Physical Habitat Assessments

Fathead Minnow Pimephales promelas

Cyprinidae (Minnows)
Trophic Class
Is Exotic to Iowa?
Is Lithophilous Spawner?
Is Hybrid?
State Listing Status
Not Listed
Assessment Program Statistics

This species was found at 570 bioassessment sites, 96 rapid fish bioassessment sites, 89 fisheries assessment sites, and 13 fisheries presence-only assessment sites. In total, it was collected at 713 distinct sites, or 49.4% of the 1442 total sites monitored by the bioassessment program. It is the 9th most commonly collected species.

The Fathead Minnow was collected in 951 bioassessment sampling sessions and 159 fisheries assessment sessions. It was present in 96 rapid bioassessment sessions and 14 presence-only sessions.

The biological assessment program has collected a total of 26,526 individual Fathead Minnow specimens, ranking it the #19 most collected fish.

Species Characteristics

The Fathead Minnow has a stout body that is moderately compressed laterally with a broad flat area just before the dorsal fin. A typical Pimephales, they have a shortened and closely attached first ray in the dorsal fin and smaller, crowded scales in front of the dorsal fin. The small, terminal mouth is oblique and without a barbel. Slender, slightly hooked pharyngeal teeth are arranged in a 4-4 array. The body is dark olive above with a shade of copper or brass behind the head and along the sides. The sides are lighter with a silvery hue, and the belly is white. A dusky band or blotch appears in the front and rear rays of the dorsal fin, which helps distinguish them from the Bullhead Minnow and Bluntnose Minnow. The lateral band is faint in fish from turbid waters and prominent in fish from clear water. An incomplete lateral line, which does not reach to the caudal peduncle, has 42 to 48 scales. Intestine length is about twice the body length and the peritoneum is black. Dorsal and pelvic fins have 8 rays, while the anal fin has 7 rays, and the pectoral fins have 15 or 16 rays. Spawning males develop a swollen, black head with breeding tubercles in three rows on the snout. Typical males are light silvery behind the opercle to the pectoral fins; then a dark bar extends to the insertion of the dorsal fin followed by a light bar to about mid-way along the dorsal fin.

Species Distribution Maps

HUC12 watersheds where this species has been found