Western Blacknose Dace Rhinichthys obtusus
This species was found at 461 bioassessment sites, 103 rapid fish bioassessment sites, 108 fisheries assessment sites, and 29 fisheries presence-only assessment sites. In total, it was collected at 623 distinct sites, or 40.9% of the 1522 total sites monitored by the bioassessment program. It is the 11th most commonly collected species.
The Western Blacknose Dace was collected in 895 bioassessment sampling sessions and 244 fisheries assessment sessions. It was present in 103 rapid bioassessment sessions and 40 presence-only sessions.
The biological assessment program has collected a total of 60,367 individual Western Blacknose Dace specimens, ranking it the #8 most collected fish.
Brownish to black above, and speckled sides with dark scales giving the fish a mottled look. A dusky lateral band is outlined above by a row of light scales. Spawning males develop a pink to red-colored lateral band. The sub-terminal mouth is oblique with equal jaws, and a barbell is on the posterior tip of the lower jaw. The upper lip is attached to the snout without a groove (a feature know as a frenulum), which is characteristic of Rhinicthys. There are 62 to 71 scales in the complete lateral line. Hooked pharyngeal teeth are arranged in a formula of 2, 4-4, 2. The peritoneum is silvery-colored, and the air bladder is well developed. Dorsal and pelvic fins have 8 rays, while the anal fin has 7, and the pectoral fins have 13 to 16 rays.
Photo by John Olson. Unnamed Tributary to Walnut Creek. Dallas County Iowa.
Photo by John Olson. Unnamed Tributary to Walnut Creek. Dallas County Iowa. 20 April 2018.
Photo Credit: John Olson
Photo Credit: Carl Kurtz
Photo by Carl Kurtz
HUC12 watersheds where this species has been found