Friday, October 7, 2016

Respect the Redhorse, by Don Orth

-->Golden Redhorse Moxostoma erythrurum is one of many unappreciated and little studied fishes in the family of suckers (Catostomidae).  All sucker fishes have downward-directed mouths that create a vacuum pump action to “suck up” small organisms.  In fact, the word, Catostomidae, is derived from Greek roots meaning “downward” and “mouth.”  The genus, Moxostoma, consists of 22 species commonly referred to as redhorse and jumprock suckers.  Fossils of Moxostoma exist from the early Pleistocene, which indicates that the origin of this genus in middle North America dates back to at least 2.5 million years ago.  
Distribution of the Golden Redhorse Moxostoma erythrurum Source USGS
Moxostoma fishes are widespread primarily east of the western continental divide.  The distribution of the Golden Redhorse Moxostoma erythrurum is shown here.  It overlaps with many other species of Moxostoma.    The poster (below) developed by Olaf Nelson should assist in identifying the more common species of Moxostoma.
Identification aids for species of Moxostoma, Poster by Olaf Nelson.
 The Golden Redhorse is aptly named for the golden scales on its body.   Other characteristics include a slate gray tail, a concave dorsal fin, and plicate lips.   

Golden Redhorse    Source:  Fishes of Georgia Gallery,
The mouth of the Golden Redhorse can protrude far from the snout during feeding.  Plicate lips of the Golden Redhorse are folded lengthwise (see photo).    Other redhorse suckes have lip textures that are a mix of plicae and papillae (individual bumps).    The lips are covered with taste buds that allow the Golden Redhorse to taste their food before sucking it in.  
Lips of the Golden Redhorse.  Photo by Jim Negus
Food selection and retention is also done by a palatal organ, which is a thick pad covered with taste buds located at roof of the pharynx. Non-food items are detected by the palatal organ and spit out.  Food particles are processed and moved to the esophagus by pharyngeal bones and teeth.    Golden Redhorse will eat many types of crustaceans, immature insects (i.e, caddisflies, mayflies, and midges), fish eggs and larvae, small molluscs and crayfishes.  However, the pharyngeal teeth are smaller and better adapted for processing macroinvertebrates than for crushing molluscs.   
Pharyngeal teeth from Golden Redhorse (A) and River Redhorse Moxostoma carinatum (B)  Source: Bailey (1951)

Golden Redhorse live in streams and rivers and orient their bodies to the current  and the stream bottom.  When observed they may be cruising together in large schools in pools or, if strong currents are present, they are at the stream bottom with their pectoral fins used to increase friction and reduce lift.  

Golden Redhorse spawn in April and May (water temperatures ~ 10 C, or 50 F) and often migrate upstream and into smaller tributaries to locate suitable spawning grounds.   Spawning habitats selected tend to have moderate-to-fast current velocity over gravel-size substrates.  Spawning depths are variable; however, the Golden Redhorse are most visible on shallow spawning habitats.
Map of a spawning area showing locations of territorial males (Kwak and Skelly 1992).
In shallow riffles the spawning males are territorial and females may cruise over spawning areas from a nearby deeper holding area.  Males use tubercles to touch and prod females to release eggs.  Rapid body movements disturb the gravel substrate so that the adhesive, demersal eggs are buried.  Repeated disturbances of gravel leave behind pits. Spawning may occur during day and night and typically two males spawn with one female.   Watch this video of River Redhorse Moxostoma carinatum spawning. Females produce between 5,000 and 25,000 eggs, depending on body size; many newly deposited eggs are quickly eaten by predators.

Boldly striped breeding male Golden Redhorse  Source Page and Johnston (1990)
Breeding male Golden Redhorse develop tubercles.  Breeding tubercles are keratinized epidermal structures that play a role during contact between spawning individuals.  The tubercles on Golden Redhorse develop about the head, body and fins and are formed by many cells that have been keratinized. 
Breeding tubercles on Golden Redhorse.  Source:  Fishes of Georgia gallery, 
The common name, redhorse, comes from a old method of capture called snaring; snaring is now outlawed by many states.   Snaring of redhorse occurred during the spawning  season when the males were holding on territories in shallow water.  Snaring involved   “using a twelve- or fourteen-foot cane  pole tipped with a loop made of a guitar string, with a little piece of lead on the bottom of the wire loop, to catch big river sucker by the tail”  (Brown 2006,   p. 12).   Brown further explains that “The sliding lead weight was to drag along the bottom and so keep the plane of the wire loop at right angles to the current. The overall aim was not to catch the Redhorse by the tail with the noose, or snare, but just behind the gills and in front of the pectoral fins. Too big a loop and it would go completely over the fish without snaring it. When you got the noose positioned just right, you had hold of a strong fish of from three to six or more pounds with head and tail free, and no give in the wire: “They’ll horse, too, they’ll pull. They’re a lot of fun.” "
A typical wire-loop apparatus for snaring Redhorse.  Photo by Jim Brown (2006). 
Redhorse spawning in the shallows are also easy targets for sharpshooters with rifles.   Scott County, Virginia, is the only remaining locality that permits the shooting of suckers.  A proposal to disallow it for safety concerns and effects on non-target fish and mussels was rejected by the Board of the VDGIF in 2014.  Although the rationale appeared to be sound, a Board member said  “It is the DGIF’s task to preserve as many outdoor pastimes as possible, even the quirky ones, while doing so with an eye toward safety, ethics and sound biology. As for shooting fish, the staff needs to do more homework.”  

Golden Redhorse are bona fide “roughfish” that are caught by many anglers by hook and line.  This video demonstrates one technique.    Redhorse  are also caught as bycatch by catfish anglers.  

A Golden Redhorse landed by a young angler.
The combination of high fecundity, rapid early growth, long life span,  specialized invertebrate feeding, and migratory habits contribute to population resilience.  Threats are often related to large-scale habitat change, such as construction of dams or diversions that inhibit recolonization after local dissappearance. Redhorses are fish that need to swim. Dams get in the way and work on passage is needed throughout their range. 

The Golden Redhorse and all members of the genus Moxostoma deserve our respect.    Fortunately, there is a nascent movement to “Respect the Redhorse.”    A website  maintained by Olaf Nelson (follow on twitter @moxostoma) promotes fishing for redhorse and other roughfish.    The website has a special section for the redhorses.  Roughfish gives a Redhorse Master Award to individuals who have caught six or more species of redhorse.  Now that is a newfound respect for the redhorse and the redhorse angler. 

Bailey, R.M. 1951.  A check-list of the fishes of Iowa, with keys for identification.   Pages 187-238  in J.R. Harlan and E.B. Speaker, Editors.  Iowa Fish and Fishing.  State Conservation Commission Of Iowa, Des Moines. 
Brown, J. 2006.  River redhorse and the seasonal snaring thereof in Alabama.  Tributaries 9:9-26.   
Curry, K.D., and A. Spacie.  1984.  Differential use of stream habitat by spawning catostomids.  American Midland Naturalist 111:267-279.
Kwak, T.J., and T.M. Skelly.  1992.  Spawning habitat, behavior, and morphology as isolating mechanisms of the golden redhorse, Moxostoma erythrurum, and the black redhorse, M. duquesnei, two syntopic fishes.  Environmental Biology of Fishes 34:127-137.
Meyer, W.H.  1962. Life history of three species of redhorse (Moxostoma) in the Des Moines River, Iowa. Transactions of the American Fisheries Society 91:412-419.
Page, L.M., and C.E. Johnston.  1990.  Spawning in the creek chubsucker, Erimyzon oblongus, with a review of spawning behavior in suckers (Catostomidae). Environmental Biology of Fishes 27:265-272.


  1. Thanks for helping spread the word about one of North America's coolest fish families, and thanks for mentioning my site ( As far as the origin of the name Redhorse, the one mentioned in Brown 2006 is probably not it. In years of digging, I've never seen that one anywhere else, and it's more likely a coincidence that the speaker used that verb to describe the fish's strength. The two most common explanations of "horse" in the name are that in profile the head of a redhorse resembles that of a horse (more true of some species than others), or that it's a reference to the large size (and I suppose that would also mean strength) of these fish. It's interesting to note that the Blue Sucker (Cycleptus elongatus) used to be known as the Blackhorse (see Additional examples of large mammal names being given to suckers are the several species of buffalo in the genus Ictiobus.
    One correction: the young angler (who happens to be my daughter) is holding a Black Redhorse (though when I took that photo I thought it was a Golden). The whole story is here:
    Again, great article! Always very excited to see my friends in the sucker family getting positive attention.

  2. Thanks for your are right about the likelihood of multiple origins to the name..I am still digging got the origins of the horsey outlines, which is reasonable but haven't found right source yet. Thanks for re ID of Iris. Will correct this and update the post. Respect the and the entire under appreciated family of fish.