The rainbow darter grows to an average length of one and one-half to two and one-half inches and may attain a maximum length of three inches. The deep body has dark bars on the sides. The bars are blue on the male and brown on the female. The typical rainbow darter has a brown back, a yellow, green or red belly and dorsal, tail and anal fins that are red with a blue edge. The lateral line is incomplete.
The rainbow darter lives in creeks and rivers, selecting areas with a gravel or rock bottom. This fish lives near the bottom. It spawns from March through May. Eggs are buried in gravel. Large males defend a territory. The rainbow darter eats crustaceans, snails and insects.