Hybognathus from the Big Blue River tend to have fewer, larger scales than H. n. placita from the Walnut River, Kansas, but more and smaller scales than H. n. nuchalis from Wisconsin. In specimens from the Blue River, the size of the orbit divided by standard length, and the width of gape divided by standard length and width of orbit, are also intermediate between the Walnut River and Wisconsin specimens, but tend toward the former. Specimens from the Big Blue River resemble H. n. placita from the Walnut River in body shape, robustness, and in the embedding of scales on the nape.
Pimephales notatus (Rafinesque), bluntnose minnow: Meek (1895:136); and Evermann and Cox (1896:399). Stations 2-S, 3-S, 5-G, 6-S, 8-S, 9-G, 10-G, 11-G, 12-G, 13-G, 16-G, 19-G, 27-G, 29-G, 53-S, 54-G, and 58-G.
The bluntnose minnow preferred the clearer creeks, with gravel or gravel-silt bottoms, but occurred rarely in the mainstream of the Big Blue River. Males and females in high breeding condition were taken on July 14, 1958. The temperature of the water was 75.5° F.
Pimephales promelas Rafinesque, fathead minnow: Meek (1895: 136); and Evermann and Cox (1896:397-398). All stations excepting 1-S, 4-S, 12-G, 30-M, 43-S, 44-S, and 56-S.
Small muddy streams were preferred by P. promelas; however, the fathead minnow was taken in all habitats, and in association with most other species.
Canfield and Wiebe (1931:6-7) may have recorded P. promelas from the Big Blue River Basin, Nebraska, as "blackhead minnows."
Campostoma anomalum plumbeum (Girard), stoneroller. All stations excepting 1-S, 2-S, 3-S, 14-S, 15-S, 21-G, 22-G, 28-G, 30-M, 33-M, 34-M, 35-M, 36-M, 37-M, 38-S, 41-S, 44-S, 45-M, 51-M, 52-S, and 55-M.
Stonerollers were usually taken in riffles with gravel-rubble bottoms. Those individuals collected in areas with mud or sand bottoms were almost invariably in the current, or in the edge of currents.