Redhorse species are members of the Catostomidae family, commonly called the sucker fishes. They are toothless (hence “sucker”), jawed fishes, each with soft fin rays, one continuous dorsal fin, a forked tail, a scaleless head, and a smooth-edged scaled body. They are often mistaken for carp species and goldfish, which have stouter bodies and one saw-tooth spine in their dorsal and anal fins.
Redhorse species are large, bottom-feeding sucker fish, each with a downturned mouth and a long, slender body. These fishes are native to North America and can be found in small to large rivers and even lakes. They prefer clear, fast-moving water with firm bottom substrate, but have been found in turbid pools.
In Illinois, five redhorse species can be found throughout most of the state—shorthead redhorse (Moxostoma macrolepidotum), golden redhorse (M. erythrurum), black redhorse (M. duquesnei), river redhorse (M. carinatum), and silver redhorse (M. anisurum).
The shorthead redhorse can be easily distinguished from other redhorse species by its bright red tail, short head, and the strong inward curve of its dorsal fin. Its sides are gold to silver and it has dark olive-brown on its back and downturned sucker mouth with the rear margin of the lower lip nearly straight. An adult can reach up to 2 feet in length, but is normally around 9 to 16 inches.
Like other redhorse species, the shorthead redhorse cannot tolerate heavy human modifications to its habitat, although it has been found to be more adaptable in its habitat requirements than other species in its genera. It consumes macroinvertebrates and small amounts of plant matter off the bottom in rocky areas.
When small, redhorse species are important forage fish for some larger game fishes, and are valuable commercial fish in large rivers where they can reach greater sizes.
INHS Illinois River Biological Station scientists have collected redhorses throughout the entire length of the Illinois River during their long-term sampling efforts, with more individuals being common in the upper Illinois River. The Kankakee River—which forms the Illinois River with the Des Plaines River near Channahon, Illinois—is known to have a high population of redhorse species. Golden redhorse and shorthead redhorse are the two most collected species during annual sampling.
