Adult fathead minnows are small in size and can range from 43 to 102 millimeters in length, although the average length is 50 millimeters. Mature males have nuptial tubercles and an elongate pad extending in a narrow line from the nape to the dorsal fin. The sides of the bodies of males become almost black except for two wide vertical bands which are light in color. The females are drab in comparison.
The fathead minnow is a freshwater fish widely distributed in the United States and it is usually found in brooks, ponds, and small lakes. The species is tolerant of high turbidity, high temperatures, and low oxygen concentrations.