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largescale stoneroller

largescale stoneroller (Campostoma oligolepis)
Photo © Isaac Szabo/Engbretson Underwater Photography

Features and Behaviors


The largescale stoneroller may attain a length of 12 inches but is usually about eight inches long. It is a dark-brown minnow with patches of brown or black scattered over the body. The lower jaw has a hard edge that is used for scraping algae when feeding. The fins are short and rounded. The bluntly rounded snout projects beyond the mouth. Teeth are present in the throat. The breeding male has white at the base of the dorsal fin and some orange on the sides.


The largescale stoneroller may be found in the northern one-third of Illinois plus McLean County. It lives in schools near the bottom of creeks with gravel, bedrock or mixed sand and gravel substrates, staying in the riffles and race-ways. This fish is intolerant of turbidity, slow flow and silt. Spawning occurs in June. The male builds a nest by digging with the fi ns, pushing pebbles with the snout and carrying pebbles in the mouth. The nest is often used by several males. The female moves to the nest and lays about 1,000 eggs. The largescale stoneroller eats algae.

Illinois Range


Kingdom: Animalia​
Phylum: Chordata​
Class: Actinopterygii​
Order: Cypriniformes​
Family: Leuciscidae

Illinois Status: common, native