The Iowa darter averages about two and three-fourths inches in length. It is a brown or green-brown fish with eight to 10 dark marks on the back and 10 to 14 dark blotches on the side separated by red spaces. There is a dark, teardrop mark under the eye and a dark bar in front of the eye, as well as bars on the fins. The lateral line is short, extending to about the second dorsal fin. There are two spines in the anal fin. The cheeks have scales. The breeding male has a blue tint to the back, green side blotches separated by rust-red spaces, wide bands of blue and orange in the first dorsal fin and orange along the lower sides.
The Iowa darter may be found in glacial lakes in northeastern Illinois, a few streams in northern Illinois and a few limestone quarries in Vermilion County. It lives in clear lakes, sloughs and creeks that have many aquatic plants. In streams it can be found in quiet pools over a mud or clay bottom with dead material and brush. Spawning occurs in April in shallow water over roots, vegetation or debris. The young Iowa darter eats plankton, while the adult feeds on immature insects and small crustaceans.