About Hybognathus nuchalis Agassiz, 1855
The Mississippi silvery minnow (Hybognathus nuchalis Agassiz, 1855) gets its common name partially from its appearance. Most of its body is covered in highly reflective silver scales, with a thick dark stripe running along the center of its back. Adults average between 12 and 13 centimeters (4.7 to 5.1 inches) in length. This species has a lateral line on each flank, one pair of pectoral fins, and one pair of small pelvic fins. Like many other minnows, it has an anal fin, a dorsal fin, and a strong caudal fin, with the dorsal fin positioned exactly midway between the head and the caudal fin. All of its fins lack markings and are transparent. It closely resembles the cypress minnow in appearance. This minnow is native to North America. It has been recorded in lowland areas of the Mississippi River basin, ranging from Minnesota south to Ohio, and has been documented throughout the Mississippi River all the way to the Gulf of Mexico. It is commonly found in small streams just upstream of their confluence with larger streams or rivers. Confirmed records of the species also exist in Illinois, Alabama, Texas, Pennsylvania, and New Mexico. It primarily inhabits freshwater river basins, shallow ponds, and shallow low-gradient streams. It is classified as a benthopelagic feeder, and feeds in large schools of other Mississippi silvery minnows. Its diet consists mainly of benthos (the flora and fauna living on the river bottom or within sediment) and small free-swimming organisms. Female Mississippi silvery minnows distribute their eggs across soft mud on the stream bottom. Offspring hatch in early summer, with hatching timing varying by location; for example, hatching occurs in late April in Wisconsin. Eggs average 0.8mm in diameter. Neither male nor female Mississippi silvery minnows provide parental care, and the species has never been documented defending territory.
