River chub

During the breeding season, sexually mature males develop pinkish-purple coloration, and swollen heads with tubercles between the eyes and snout tip (they are sometimes called hornyheads).

[4] The river chub is found in clear, medium to large creeks and rivers with moderate to swift current over rock and gravel substrate, from southeast Ontario and southern New York to Michigan and Indiana, south to northwest South Carolina to northwest Alabama.

[11][12][13] Fresh-water mussels release small masses of microscopic larvae known as glochidia in a loose gelatinous matrix.

[11][12] The river chub is host to mussels including the endangered fine-rayed pigtoe, Tennessee clubshell and probably many other amblemine glochidia.

[11][12] Nest associates of the river chub include species of the Clinostomus, Luxilus, Lythrurus, Notropis, Chrosomus, Rhinichthys, and Semotilus genera.

In late spring the breeding male builds a pebble nest close to the bank of the stream in low to moderate current.

[14] In early spring the adult male river chub undergoes pronounced changes in his appearance in preparation for breeding.

Small tubercles grow on the outer part of his first several pectoral fin rays and his body develops a pinkish-purple coloration.

When a gravid female enters the trough he presses her against the side by placing his caudal peduncle over hers and lodging her head between his opercle and pectoral fin.

Like many minnow species it requires flowing water over coarse substrate to reproduce so dams impact its range negatively.

This sediment-starved condition has impacted some species, such as the redd nesting northern hog sucker and black redhorse, that require natural deposits of coarse material to spawn, but typically the river chub continues to be able to find gravel to build its own spawning habitat.

Limestone treatments and wetlands were built to mitigate the acid mine drainage and the river chub was one of the first species to return.