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

Creek Chub Semotilus atromaculatus

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 758 bioassessment sites, 168 rapid fish bioassessment sites, 111 fisheries assessment sites, and 45 fisheries presence-only assessment sites. In total, it was collected at 960 distinct sites, or 71.2% of the 1349 total sites monitored by the bioassessment program. It is the 1st most commonly collected species.

The Creek Chub was collected in 1568 bioassessment sampling sessions and 299 fisheries assessment sessions. It was present in 168 rapid bioassessment sessions and 52 presence-only sessions.

The biological assessment program has collected a total of 114,805 individual Creek Chub specimens, ranking it the #2 most collected fish.

Species Characteristics

Body form is stout and robust, with a broad, blunt head. There is a black spot in the first 3 rays of the dorsal fin. It has a very large mouth. A small, flap-like barbel is located in the groove in the middle of the upper jaw. A wedged-shaped spot appears at the base of the tail. Body color of the back and sides varies from olive to purplish changing to silvery-white on the belly, and a lateral stripe runs from the tip of the snout through the eye to the end of the caudal peduncle. The intensity of the lateral stripe and dorsal color depends on water clarity, darker individuals come from clearer waters. Creek Chubs look striped because of the dark color above, light streak just above the dark lateral line, and then white beneath. The dorsal fin is behind the base of the pelvic fins, and the anal fins have 8 rays, while the pectoral fins have 16 or 17, and the pelvic fins have 8 rays. Body scales are very small and look cross-hatched on the upper back and sides. Lateral line scales range from 49 to 64, and are sometimes interrupted by missing pores. A terminal, slightly oblique mouth extends to below the eye and usually has a barbel; the barbel may be absent from one or both sides. Hooked pharyngeal teeth, on stout arches, are arranged in two rows and have the formula 2, 5-4, 2. Breeding males develop a rosy tint on the body and form large nuptial tubercles on the head and snout. Fins may become light yellowish to light olive in color.

Species Distribution Maps

HUC12 watersheds where this species has been found