The Topeka shiner (Notropis topeka), an endemic minnow of the Great Plains, has been extirpated over much of its former range. The U.S. Fish and Wildlife Service listed it as an endangered species in January 1999. The only extant population of N. topeka remaining on the High Plains is located in northwestern Kansas. During 1999, we studied aspects of the natural history of this isolated population. Notropis topeka fed in aggregations comprised of central stonerollers (Campostoma anomalum), fathead minnows (Pimephales promelas), green sunfish (Lepomis cyanellus), orangespotted sunfish (Lepomis humilis), and orangethroat darters (Etheostoma spectabile). Notropis topeka also raided the nests of P. promelas to consume eggs. Nests of N. topeka were located on the periphery of L. cyanellus nests, and possibly on the periphery of L. humilis and P. promelas nests. We describe the spawning act of N. topeka on the periphery of L. cyanellus nests, as well as their interspecific behavior near the nests of L. cyanellus, L. humilis, and P. promelas.