Breeding occurs between late April and late August, when male redfin shiners aggregate in dense swarms at spawning grounds. The females remain in deep water until ready to spawn. Each male defends a territory over a sunfish (Lepomis) nest, into which the eggs are cast. The male and female redfin shiner swim parallel while the male stimulates the female to release the eggs with vibrations of its body (9).
A surface feeder (4), the redfin shiner mainly eats aquatic and terrestrial insects or other small invertebrates, but often feeds extensively on algae (7).