Freshwater Fish - Species

Robust Redhorse (Moxostoma robustum)

Description: (Anatomy of a Fish)
The Robust Redhorse is a large cylindrically shaped member of the sucker family. Its upper body has a coppery bronze body color that transitions into a white underbelly. Young fish have vivid red fins that fade with age and increased size, only to brighten again during spawning season. Like all sucker species, the Robust Redhorse has an underslung mouth adapted for ingesting bottom dwelling animals.

Range: The Savannah River, the Santee Drainage (re-introduction underway), and the Pee Dee River.

Average Length: Adults range from 20 to 30 inches

Average Size: Up to 18 pounds

Life Expectancy: in excess of 27 years

Preferred Habitat

Robust Redhorse inhabit large rivers. They are found from the rocky reaches of the mid-piedmont, downstream into the coastal plain. They require gravel bars for spawning and these occur primarily in the transition zone between the piedmont and coastal plain.

Food Habits

• Adult Robust Redhorse have specialize pharyngeal teeth that are adapted for crushing the shells of mollusks.
• Adults consume exotic corbicula clams that are found in abundance throughout South Carolina’s rivers and lakes.

Spawning

• Spawning occurs in the spring when water temperatures reach about 70 degrees Fahrenheit.
• Males establish and defend territories on suitable mid channel gravel bars, where two males and one female will spawn and simultaneously bury fertilized eggs.
• Suitable gravel bars have fast flowing water that sufficiently infiltrates the gravel, providing enough oxygen for proper egg development.
• Dam construction that impeded natural spawning migrations and gravel choking siltation from past farming practices have been implicated in the decline of this species.

Miscellaneous

Robust Redhorse went unnoticed for nearly a century after their description by Edward Cope in 1870. Their distinctive pharyngeal teeth have been found at Native American archaeological sites in the Pee Dee, Santee, and Savannah River Basins, indicating that they were a part of the Native American diet. Robust Redhorse spawning behavior on shallow gravel bars and upstream spring migration leave them particularly vulnerable to the artisanal fishing with spears and weirs. The remnants of Native American fishing weirs can still be observed on the Broad River.

Literature Cited