Goldeyes and Mooneyes

North American freshwater fishes of the family Hiodontidae (order Hiodontiformes or Osteoglossiformes) include the goldeye (Hiodon alosoides) and mooneye (H. tergisus). The goldeye ranges from James Bay (bordering the provinces of Ontario and Quebec) in Canada and the Mississippi River basins from the Northwest Territory to western Pennsylvania and Ohio south to Louisiana. In Arkansas, H. alosoides is found sporadically in lakes and the larger turbid rivers of the state, including the Arkansas and Mississippi, and the smaller Black River. The mooneye (also called the “freshwater tarpon”) ranges from the St. Lawrence–Great Lakes, Mississippi River, and Hudson Bay basins from Quebec and Alberta, Canada, east to western North Carolina and south to Louisiana. In Arkansas, H. tergisus occurs in large but also smaller rivers, including the Arkansas, Black, Current, Little Red, Ouachita, Spring, Strawberry, and White rivers but rarely in the more turbid Mississippi River.

Hiodontids date in the fossil record to the late Eocene Epoch (lasting from fifty-six to thirty-four million years ago). It has been hypothesized that their closest relatives are the African knife fishes (family Notopteridae). There are four extinct species of Hiodon, and one of them, H. consteniorum, was discovered in the Kishenehn Formation exposed along the Middle Fork of the Flathead River in northwestern Montana.

Members of the genus Hiodon are distinguished by a long anal fin with twenty-three to thirty-three rays that is not confluent with the deeply forked caudal fin and by the presence of distinct pelvic fins. Both fish are silvery (herring-like), iridescent, and strongly compressed, with large eyes, scaleless heads, cycloid scales that lack spines, a single dorsal fin, an adipose eyelid (like herrings), well-developed lateral lines, abdominal pelvic fins, an axillary process at the base of the pelvic fin, and prominent teeth on the jaws and tongue. While they are morphologically similar to each other, the mooneye has a deeper body, its dorsal body outline is curved rather than straight, its anterior insertion of the dorsal fin is greater, and it possesses eleven or twelve dorsal fin rays (vs. nine or ten in H. alosoides); also, the iris of the eye is somewhat larger, with silvery rather than a vivid golden pigment found in goldeyes.

Adult goldeyes average 47 cm (19 in.) in length and can weigh from 450 to 900 g (one to two pounds). They feed on a wide variety of organisms, including insects, crustaceans, small fish, mollusks, and even frogs and mice. The age of first reproduction for goldeyes has been reported to be from six to nine years for males and seven to ten years in females. However, sexual maturity varies with latitude, being much earlier for fish in the southern latitudes than in the northern ones. Spawning of 6,000 to 25,000 eggs occurs in late May or early June and is characterized by 4 mm (in diameter) eggs that are semi-buoyant. Interestingly, this is a rare trait in freshwater fishes, being more common in marine fishes. The eggs are suspended in the aqueous environment, where they drift downstream or to quiet waters. After hatching, the majority of growth occurs between June and September. The lifespan of H. alosoides can be up to seventeen years.

The goldeye is considered a Species of Greatest Conservation Need in Arkansas by the Arkansas Game and Fish Commission, and it is listed as S2 (imperiled) by NatureServe. There are relatively few records with voucher specimens in state museum collections; however, its alleged scarcity probably results more from a lack of collecting in the big river habitats in the state with special gear (boat electrofishers, Missouri Trawl, or gill nets) than from actual scarcity. Indeed, several adult H. alosoides were collected by researchers in a Missouri Trawl in 2015 from the Mississippi River (Arkansas side) at Sans Souci Landing south of Osceola (Mississippi County).

The mooneye lives in clear waters of lakes, ponds, and rivers and is mostly intolerant of turbid waters. Adults reach an average length of 30 cm (11.7 in.) but can be up to 47 cm (19 in.) and weigh an average of 226 g (8.0 oz.). They are surface feeders that primarily consume aquatic and terrestrial insects, but they are also known to eat crustaceans, mollusks, and small fishes. Young mooneyes eat larval mayflies, caddisflies, and midges during the first few months of life. Predatory fishes including pikes and walleye are known to feed on Hiodon spp. as well as birds (cormorants) and fish-eating mammals.

Like its relative, the mooneye is mostly a spring spawner. Each spring, adults migrate upstream to clearer running waters with solid substrates to spawn where females are capable of producing 10,000 to 20,000 semibuoyant eggs each year. Newly hatched fry are eight to nine mm (0.31–0.35 in.) in length and exhibit rapid growth during their first year, reaching up to 20 cm (7.9 in.). Males reach sexual maturity at three, whereas females reach maturity at four to five years and continue to spawn every year thereafter. The lifespan for males is about seven years, and females live up to nine years.

The mooneye is considered S3 (vulnerable) in Arkansas by NatureServe and is listed by the Arkansas Game and Fish Commission as a Species of Greatest Conservation Need. It has declined in numbers in many parts of its range and is uncommon in the state.

Both fish are considered good fly-fishing fishes and can be taken with dry flies or with jigs, but they are unpopular with most fishermen because of their small size. However, the famous American ichthyologist David Starr Jordan (1851–1931) elegantly described the angling qualities of the mooneye thusly in 1923: “They are eager biters and take indiscriminately the feathered lures, small spoons, grasshoppers, grubs, and other natural bait.”

In Arkansas, goldeyes are taken in summer by fishermen using minnows in the Arkansas River. The goldeye is also preferred by many consumers as a smoked product, and some commercial fishermen sell them smoked after being processed (marinated) in a brine made of various spices.

Concerning parasites, three trematodes specific to H. tergisus are Crepidostomum hiodontos, Paurorhynchus hiodontis, and Plagioporus tergisus. A caryophyllidean tapeworm, Bothriocephalus texomensis, is specific to H. alosoides and was described from specimens collected at Lake Texoma, Oklahoma. There are also a number of other parasites of these fish, including nematodes, acanthocephalans, and crustaceans.

For additional information:
“Arkansas Endangered, Threatened, Regulated, and Species of Greatest Conservation Need.” Little Rock: Arkansas Game & Fish Commission, 2016.

Battle, Helen I., and William M. Sprules. “A Description of the Semi-Buoyant Eggs and Early Developmental Stages of the Goldeye, Hiodon alosoides (Rafinesque).” Journal of the Fisheries Research Board of Canada 17 (1960): 245–266.

Douglas, Neil H. The Fishes of Louisiana. Baton Rouge: Claitor’s Publishing Division, 1974.

Etnier, David A., and Wayne C. Starnes. The Fishes of Tennessee. Knoxville: University of Tennessee Press, 1993.

Hoffman, Glenn L. Parasites of North American Freshwater Fishes. 2nd ed. Berkeley: University of California Press, 2009.

Jordan, David S., and William F. Thompson. “Note on the Goldeye, Amphiodon alosoides (Rafinesque) or Ellatonistius chrysopsis (Richardson).” Proceedings of the United States National Museum 38 (1910): 353–357.

Katechis, Costas, Peter Sakaris, and Elise R. Irwin. “Population Demographics of Hiodon tergisus (Mooneye) in the Lower Tallapoosa River.” Southeastern Naturalist 6 (2007): 461–470.

Lee, David S., Carter R. Gilbert, Charles H. Hocutt, Robert E. Jenkins, Donald W. McAllister, and Jay R. Stauffer Jr. Atlas of North American Freshwater Fishes. Raleigh: North Carolina State Museum of Natural History, 1980.

Li, Guo-Qing, and Mark V. H. Wilson. “An Eocene Species of Hiodon from Montana, its Phylogenetic Relationships, and the Evolution of the Postcranial Skeleton in the Hiodontidae (Teleostei).” Journal of Vertebrate Paleontology 14 (1994): 153–167.

Martin, Mayo. “Age and Growth of the Goldeye, Hiodon alosoides (Rafinesque) of Lake Texoma, Oklahoma.” Proceedings of the Oklahoma Academy Science 33 (1952): 37–49.

Mettee, M. F., P. E. O’Neil, and J. M. Pierson. Fishes of Alabama and the Mobile Basin. Birmingham: Oxmoor House, 1996.

Miller, Rudolph J., and Henry W. Robison. Fishes of Oklahoma. Norman: University of Oklahoma Press, 2004.

Nelson, Joseph S., Terry C. Grande, and Mark V. H. Wilson. Fishes of the World. 5th ed. New York: John Wiley and Sons, 2016.

Page, Lawrence M., and Brooks M. Burr. Peterson Field Guide to Freshwater Fishes of North America North of Mexico. 2nd ed. Boston: Houghton Mifflin Harcourt, 2011.

Pflieger, William L. The Fishes of Missouri. Jefferson City: Missouri Department of Conservation, 1997.

Robison, Henry W. “Fishes of the Pine Bluff Arsenal, Jefferson County, Arkansas.” Journal of the Arkansas Academy of Science 59 (2005): 148–157. Online at http://scholarworks.uark.edu/cgi/viewcontent.cgi?article=1546&context=jaas (accessed December 11, 2018).

Robison, Henry W., and Thomas M. Buchanan. Fishes of Arkansas. 2nd ed. Fayetteville: University of Arkansas Press, 2020.

Ross, Stephen T. The Inland Fishes of Mississippi. Jackson: University Press of Mississippi, 2001.

Stauffer, Jay R., Jr., Jeffrey M. Boltz, and Laura R. White. “The Fishes of West Virginia.” Proceedings of the Academy of Natural Sciences of Philadelphia 146 (1995): 1–389.

Trautman, Milton B. The Fishes of Ohio. Columbus: Ohio State University Press, 1957.

Tumlison, Renn, Chris T. McAllister, Henry W. Robison, Matthew B. Connior, D. Blake Sasse, David A. Saugey, and Stephen Chordas III. “Vertebrate Natural History Notes from Arkansas, 2016.” Journal of the Arkansas Academy of Science 70 (2016): 248–254. Online at http://scholarworks.uark.edu/cgi/viewcontent.cgi?article=2210&context=jaas (accessed December 11, 2018).

Wallus, R., and J. P. Buchanan. “Contributions to the Reproductive Biology and Early Life Ecology of Mooneye in the Tennessee and Cumberland River.” American Midland Naturalist 122 (1989): 204–207.

Warren, Melvin L., Jr., and Brooks M. Burr. Freshwater Fishes of North America. Vol. 1: Petromyzontidae to Catostomidae. Baltimore: Johns Hopkins University Press, 2014.

Chris T. McAllister
Eastern Oklahoma State College