Bowfin

aka: Grinnell

Bowfin (Amia calva) belong to the primitive North American fish family Amiidae and Order Amiiformes. The family is monotypic and contains a single genus and species (A. calva). Bowfin are basal bony fishes related to gars in the infraclass Holostei. They are native to North America and are commonly found throughout much of the eastern United States, the St. Lawrence River, and Lake Champlain drainages of southern Ontario, and Quebec, Canada. Their range extends farther westward around the Great Lakes into Minnesota and south to the Colorado River in Texas. In Arkansas, A. calva is found in all major river drainages of the Gulf Coastal Plain lowlands and westward through the Arkansas River Valley; they are rarely found in the uplands (Ozarks and Ouachitas) of the state.

The order Amiiformes, which persists to the present, dates from the Jurassic (about 150 million years ago) to the early Eocene (about 50 million years ago). Although bowfin are highly evolved fishes, they are often referred to as “relicts” or “living fossils” because they have retained some early ancestral morphological characteristics. The family Amiidae is the sister group to all higher teleost (bony) fishes.

Bowfin are found in vegetated sloughs, lowland rivers, weedy lakes, swamps, and backwater areas; they are also occasionally found in brackish water. In Arkansas, they occur in bayous, oxbow lakes, rivers, swamps, and even creeks such as Fourche and Brodie creeks in Little Rock (Pulaski County). They tend to prefer clear, quiet waters with abundant aquatic vegetation and avoid areas with swift current and excessive turbidity. There are various colloquial names for bowfin, including grinnell, cypress trout, dogfish, mudfish, mud pike, and choupique.

Bowfin possess an elongated and cylindrical body, with coloration on the sides and back ranging from brown to olive-green, often with vertical bars and dark mottling or reticulations, or a camouflage-like pattern. The upper base of the abbreviate-heterocercal (modified) caudal fin has a large halo-like black “eye” spot that is most evident in young males, whereas the adult male has one bordered with orange or yellow; those of the females are less distinct. Although not proven, it is thought the purpose of the eyespot is to confuse predators, directing attacks to its tail rather than the head, which may allow the bowfin to escape predation. The venter of bowfin is white or cream colored, and the paired fins and anal fin are bright green. The dorsal fin contains forty-six to fifty soft rays, there are numerous sharp teeth on the upper and lower jaws, and the body (except for the head) is covered with cycloid-type scales. The nostrils are very prominent and each possesses a prominent barbel-like flap and a gular plate (a flat plate on the floor of the mouth). Bowfin possess a complete lateral line with sixty-four to sixty-eight scales.

Bowfin average about 50 cm (20 in.) in length, and females are usually larger than males. The world angling record stands at 9.8 kg (21.5 lbs.) and represents a specimen caught in 1980 in South Carolina. In Arkansas, the state bowfin record is a specimen weighing 7.9 kg (17 lbs., 5 oz.) caught in 1977 in Desha County.

This fish is a piscivorous nocturnal stalker; it ambushes prey by moving into shallower waters at night, where adults feed on gizzard shad, golden shiners, bullhead catfish, and sunfishes. It will also take aquatic invertebrates, including crayfish, mollusks, and insects. Young bowfin feed on microcrustaceans and, once they reach 40 mm in length, switch to aquatic insects. Food critics have given a delicacy made from bowfin eggs called “Cajun caviar” positive reviews. However, bowfin flesh is not thought of as food for most people. Bowfin are known to be excellent fighters and are often caught by anglers who use natural bait and artificial lures. Bowfin are even taken by commercial fisheries, and from 1975 to 1985, an average of over 33,000 kg (72,000 lbs.) was taken per year in Arkansas alone.

Bowfin achieve sexual maturity at two to three years of age. Males construct circular nests in shallow water, and females spawn in the spring (April through June). They deposit from 23,000 to 64,000 adhesive eggs that stick to aquatic vegetation, roots, gravel, and sand. Once the female lays the eggs, she vacates the nest, and the male is left to guard them. Hatchlings appear in about ten days after oviposition and school with other young until they reach about 7 to 10 mm (0.3 to 0.4 in.) in length. They grow rapidly and typically leave schools within four to six weeks after hatching. By October, young have grown to about 13 to 23 cm (5.1–9.1 in.) in length. The lifespan of bowfin has been reported to be up to thirty years in captivity but about ten to twelve years in the wild.

Bowfin—like bichirs, gars, and lungfishes—respire via bimodal breathing. Their gills remove oxygen in the water, letting them exploit this respiratory gas for breathing, but they also have a gas bladder that functions to maintain buoyancy. This organ allows A. calva to breathe air by means of a small pneumatic duct connected from the foregut to the gas bladder. They also have the ability to break the surface to gulp air, which permits them to survive conditions of environmental hypoxia that would kill most other fishes.

Numerous parasites have been reported from bowfin, including protozoans, trematodes, cestodes, nematodes, acanthocephalans, leeches, crustaceans, and pentastomes. One of the more common ectoparasites of bowfin is fishlice, Argulus spp. A bowfin from Dorcheat Bayou in Columbia County was reported to be infested with an adult female Argulus americanus. However, nothing is known about internal parasites of Arkansas populations of bowfin.

For additional information:
Ashley, K., and R. Rachels. “Food Habits of Bowfin in the Black and Lumber Rivers, North Carolina.” Conference of the Southeastern Association of Fish and Wildlife Agencies 1 (1999): 50‒60.

Burgess, G. H., and Carter R. Gilbert. 1980. “Amia calva (Linnaeus), Bowfin.” In Atlas of North American Freshwater Fishes, edited by D. S. Lee, et al. Raleigh: North Carolina State Museum of Natural History, 1980.

Davis, Jonathan G. “Reproductive Biology, Life History and Population Structure of a Bowfin Amia calva Population in Southeastern Louisiana.” MS thesis, Nicholls State University, 2006. Online at https://www.nicholls.edu/bayousphere/GraduateStudents/JDavis/Davis_Thesis.pdf (accessed December 10, 2018).

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.

Helfman, Gene, Bruce B. Collette, Douglas E. Facey, and Brian W. Bowen. The Diversity of Fishes: Biology, Evolution, and Ecology. New York: John Wiley & Sons, 2009.

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

Jackson, D. C., and C. G. Farmer. “Air-Breathing During Activity in the Fishes Lepisosteus oculatus and Amia calva.” Journal of Experimental Biology 201 (1998): 943‒948.

McAllister, Chris T., William J. Poly, Donald G. Cloutman, Henry W. Robison, and Michael K. Hill. “Argulus spp. (Crustacea: Branchiura) on Fishes from Arkansas and Oklahoma: New Geographic Distribution Records.” Proceedings of the Oklahoma Academy of Science 96 (2016): 70–72.

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.

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

Pearson, J. G., and F. P. Ward. “A New Record of the Bowfin, Amia calva Linnaeus, in the Upper Chesapeake Bay.” Chesapeake Science 13 (1972): 323‒324.

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

Poly, William J. “Global Diversity of Fishlice (Crustacea: Branchiura: Argulidae) in Freshwater.” Hydrobiologia 595 (2008): 209–212.

Robison, Henry W., and Thomas M. Buchanan. Fishes of Arkansas. Fayetteville: University of Arkansas Press, 1988.

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

Shimura, S., and A. Minoru. “Argulus americanus (Crustacea: Branchiura) Parasitic on the Bowfin, Amia calva, Imported from North America.” Fish Pathology 18 (1984): 199–203.

Thomas, Chad, Timothy H. Bonner, and Bobby G. Whiteside. Freshwater Fishes of Texas: A Field Guide. College Station: Texas A&M University Press, 2007.

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

Chris T. McAllister
Eastern Oklahoma State College

Last Updated: 12/10/2018

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