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Amia calva1.jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Superorder: Holostei
Order: Amiiformes
Family: Amiidae
Subfamily: Amiinae
Genus: Amia
Linnaeus, 1766
Species: A. calva
Binomial name
Amia calva
Linnaeus, 1766

Bowfins (Amia calva) are basal bony fishes related to gars in the Superorder, Holostei.[1] Common names include mudfish, mud pike, dogfish, griddle, grinnel, cypress trout and choupique.[2][3][4] They are regarded as taxonomic relicts, being the last surviving members of both the order Amiiformes (which includes three additional, now-extinct families dating from the Jurassic to the Eocene), and of the family Amiidae which contains numerous species in about four subfamilies, only one of which, Amiinae, is extant. They are often improperly referred to as "primitive fishes" because they have retained some morphological characters common with ancestors of modern fish.[5]

Bowfins are demersal freshwater piscivores commonly found in much of the eastern United States, and in southern Ontario and Quebec. They inhabit the drainage basins of the Mississippi River, Lake Superior and Lake Michigan.[6][7] Their preferred habitat includes vegetated sloughs, lowland rivers and lakes, swamps, backwater areas, and they are also occasionally found in brackish water. They are stalking, ambush predators that will move into the shallows at night to prey on fish, and aquatic invertebrates such as crawfish, mollusks, and aquatic insects.[8]

Like the distantly related gar fishes, bowfins are bimodal breathers which means they have the capacity to breathe both water and air. Their gills exchange gases in the water allowing them to exploit oxygen for breathing, but they also have a vascularized swim bladder lung that not only serves to maintain buoyancy, it allows them to breathe air through a small duct connected from the esophagus to the gastrointestinal tract. They break the surface to gulp air, thus surviving conditions of aquatic hypoxia where most other species cannot survive.[9][10]

Description and biology[edit]

Bowfin in aquarium
Clip of bowfin activity in an aquarium.
Drawing of a bowfin skull showing the bony plates protecting the head.


The average length of a bowfin is 50 cm (20 in);[6] females typically grow to 65–70 cm (26–28 in), males to 50–65 cm (20–26 in).[11] Records indicate bowfins can reach 109 cm (43 in) in length, and weigh 9.75 kg (21.5 lb).[12] Young of the year typically grow to 13–23 cm (5.1–9.1 in) by October.[13] Females tend to grow larger than males.[14][15]

The body of the bowfin is elongated and cylindrical, with the sides and back olive in color, often with dark reticulations. The underside is white or cream. Bowfins have large scales that are technically ganoid, but actually very similar to cycloid scales of Teleostei.[16] The paired fins and anal fin are bright green. Males have a black "eye spot" on the base of the tail (caudal peduncle) that is commonly encircled by an orange-yellowish border. It is thought to confuse predators, deflecting attacks away from the head of the fish to its tail, which affords the bowfin an opportunity to escape predation.[6][13][17][18] The bowfin is so named for its long, undulating dorsal fin consisting of 145 to 250 rays, and running from the middle of the back to the base of the tail.

Bowfins are often referred to as "living fossils", and sometimes inaccurately described as "primitive" due to the retention of some primitive features of ancestral predecessors, including a modified (rounded externally) heterocercal caudal fin, a swim bladder lung, vestiges of a spiral valve, and a bony gular plate underneath the head.[5][19] A distinctive feature of bowfin is the gular plate, a bony plate[17] located on the exterior of the lower jaw between the two sides of the lower jaw bone. Other characteristics include long, sharp teeth, and two protruding tube-like nostrils.[17]

Mistaken identity[edit]

Northern snakeheads (Channa argus) are invasive piscivores fishes that are native to the rivers and estuaries of China, Russia, and Korea.[20][21] They are commonly mistaken for bowfin because of their similarities in appearance. Bowfins and snakeheads have elongated, cylindrical bodies, a long dorsal fin that runs along their backs, round tails, and sharp teeth. Both species are bimodal breathers, (can breathe both air and water), are capable of aestivation, and are found in similar habitats. Some contrasting differences in bowfins include a black "eye spot" on their caudal peduncle, a tan and olive coloration, a shorter anal fin, a more rounded head, and an upper jaw that is longer than its lower jaw.[22][23] The burbot, a predacious fish native to streams and lakes of North America and Eurasia, is also commonly mistaken for bowfin. Burbots can be distinguished by their flat head and chin barbel, long anal fin, and pelvic fins situated beneath the pectoral fins.[24]


Bowfins are capable of bimodal respiration, being able to breathe air by utilizing their gas bladder as a lung. When performing low-level physical activity, they obtain more than half of their oxygen consumption from breathing air.[25] Bowfins have two distinct air-breathing mechanisms used to ventilate the gas bladder. Type I air breaths are consistent with the action of exhale-inhale stimulated by aerial or aquatic hypoxia to regulate O2 gas exchange; type II air breaths are by inhalation alone which is believed to regulate gas bladder volume for buoyancy control.[26] Bimodal respiration helps bowfin survive and maintain their metabolic rate in hypoxic conditions.[10][27][28] The rate of air breating is higher in darkness, coincidental with the higher activity of the fish.[6]

Bowfin blood can adapt to warm, acidic waters.[13] The fish becomes inactive in waters below 10 °C (50 °F);[13] at this temperature they practically do not breathe air.[6] With increasing temperature the air breathing increases.[6] Their preferred temperature range is between 12–26 °C (54–79 °F), with 18 °C (64 °F) the temperature of maximum activity.[29] Air breathing is maximum in the 18.4–29.6 °C (65.1–85.3 °F) range.

Herpetologist Wilfred T. Neill, reported in 1950 that he unearthed a bowfin aestivating in a chamber 4 inches (10 cm) below the ground surface, 8 inches (20 cm) in diameter, .25 miles (0.4 km) from a river. It was further noted that flood levels had previously reached the area, and receded. It is not unusual for riverine species like bowfin to move into backwaters with flood currents, and become trapped when water levels recede.[6][30][31][32] While aestivation is anecdotally documented by multiple researchers, laboratory experiments have suggested instead that bowfin are physiologically incapable of surviving more than three to five days of air exposure. However, no field manipulation has been performed.[33][34]

Habitat and feeding[edit]

Bowfins are usually not easy to spot, living in clear, slow water with abundant vegetation, preferring places with roots, logs and other types of shelter.[35][36][37] Oxygen-poor environments can be tolerated because of its ability to breathe air.[36]

Bowfins are indiscriminate predators that readily prey on a broad variety of arthropod and vertebrate prey, from insects and crawfish to other fish and frogs.They ambush and stalk their prey, and are remarkably agile.[11][17] Young fish feed mostly on young crustaceans, while older fish (longer than 10 cm or 3.9 in) are mostly piscivorous.[36] The long dorsal fin is used to propel silently through water up to the last inches, when the prey is then quickly engulfed by the mouth, with a movement that lasts only 0.075 seconds[29] - this last part of the attack is similar to that of gars, but it attacks on the front rather than on the side.[35] Its feeding habits are preferentially nocturnal.[37]

Life cycle[edit]

Bowfins spawn in the spring or early summer, typically between April and June, more commonly at night[29][36] in abundantly vegetated, clear shallow water in weed beds over sand bars, and also under stumps, logs, and bushes.[38] Optimum temperatures for nesting and spawning range between 16–19 °C (61–66 °F).[15] The males construct circular nests in fibrous root mats, clearing away leaves and stems. Depending on the density of surrounding vegetation there may be a tunnel-like entrance at one side.[38] The diameter of the nests commonly range between 39–91 cm (15–36 in),[15][39] at a water depth of 61–92 cm (24–36 in).[29]

During spawning season, the fins and underside of male bowfins often change in color to a bright lime green.[40] The courtship/spawning sequence lasts one to three hours, and can repeat up to five times.[29] Courtship begins when a female approaches the nest. The ritual consists of intermittent nose bites, nudges, and chasing behavior by the male until the female becomes receptive,[15] at which time the pair lie side by side in the nest. She deposits her eggs while he shakes his fins in a vibratory movement, and releases his milt for fertilization to occur.[15] A male often has eggs from more than one female in his nest, and a single female often spawns in several nests.[41][42]

Females vacate the nest after spawning,[29] leaving the male behind to protect the eggs during the eight to ten days of incubation.[17][38][43] A nest may contain 2,000 to 5,000 eggs, possibly more.[35] Fecundity is usually related to size of the fish, so it isn't unusual for the roe of a large gravid female to contain over 55,000 eggs.[29][36] Bowfin eggs are adhesive, and will attach to aquatic vegetation, roots, gravel, and sand.[29] After hatching, larval bowfin do not swim actively in search of food. During the seven to nine days required for yolk-sac absorption, they attach to vegetation by means of an adhesive organ on their snout, and remain protected by the parent male bowfin.[35] Bowfins aggressively protect their spawn from the first day of incubation to a month or so after the eggs have hatched.[35] When the fry are able to swim and forage on their own, they will form a school and leave the nest accompanied by the parent male bowfin who slowly circles them to prevent separation.[38]

Bowfin reach sexually maturity at two to three years of age.[36] They can live ten to twelve years in the wild,[36] and 30 years in captivity.[17][38] Females are longer-lived than males.[14]


Lernaea, or anchor worm, on a Murray cod. The same parasite also attacks bowfins.

A common parasite of bowfin is the anchor worm (Lernaea). These small crustaceans infest the skin and bases of fins, with consequences ranging from slowed growth to death.[15] The mollusk Megalonaias gigantea lays eggs in the bowfin gills, that are then externally fertilized by sperm passing in the water flow. The small glochidia larvae then hatch and develop in the gill tubes.[15]

Bowfins with liver cancer and with fatal leukaemia have been reported.[13]


The bowfin is considered an evolutionary indicator, a window to the fossil past of bony fishes. Based on a mitogenetic perspective on the phylogeny of "ancient fish", the basal actinopterygians comprise four major lineages, including Polypteriformes, Acipenseriformes, Lepisosteidae, and Amia calva.[44] Following the radiation of basal actinopterygians, fossil records indicate the evolution of a new lineage of ray-finned fishes in the Late Permian Epoch which grew to prominence in the Mesozoic and Cenozoic Eras.

Neopterygians are the second major occurrence in the evolution of ray-finned fishes, and are distinguished from their earlier ancestors by major changes to the jaws, shape of the skull, and tail. Neopterygians include four main groups of fishes:

  • the semionotids (now extinct) appeared in the Permian Period, and were small, streamlined swimmers that occupied freshwater and marine habitats;
  • the lepisosteids which include extant species of garfishes that first appeared in the Cretaceous,
  • the bowfins (halecomorphids) the only extant species in the order Amiiformes which date back to the Triassic Period, and
  • the stem group of Teleostei from which modern fish arose, including most of the bony fish we are familiar with today.[45]


A man with a freshly captured bowfin.

As a sport fish, bowfin are not considered desirable to many anglers. They were once considered a nuisance fish by anglers and early biologists who believed the bowfin's predatory nature was harmful to sport fish populations. As a result, efforts were taken to reduce their numbers.[46] Research has since proven otherwise, and that knowledge together with a better understanding of maintaining overall balance of ecosystems, regulations were introduced to help protect and maintain viable populations of bowfins.[46] Bowfin are strong fighters, a prized trait in game fish. However, they do have a jaw full of sharp teeth which requires careful handling. The current tackle record is 21.5 lb (9.8 kg)[2][7][11]

Small bowfins are easy and interesting to keep in aquariums.[6]

Bowfin were once considered to have little commercial value because of its poor tasting meat which has been referred to as "soft, bland-tasting and of poor texture".[11][17] However, it is considered quite palatable if cleaned properly and smoked, or prepared fried, blackened, used in courtbouillion, or in fishballs or fishcakes.[7][11][47] Over the years, global efforts have imposed strict regulations on the international trade of caviar, particularly on the harvest of sturgeons from the Caspian Sea where the highly prized caviar from the beluga sturgeon originates. The bans imposed on Caspian sturgeons have created lucrative markets for affordable substitutes in the United States including paddlefish, bowfin, and various species of sturgeon.[48][49] In Louisiana, bowfin are harvested in the wild, and cultured commercially in hatcheries for their meat and roe. The roe is processed into caviar, and sold as "Cajun caviar", or marketed under the trade name "Choupiquet Royale".[14][29][50]

Accumulation of toxic substances[edit]

In some areas of the United States where aquatic environments have tested positive for elevated levels of toxins, such as mercury, arsenic, chromium, and copper, there are posted signs with warnings about the consumption of fish caught in those areas.[51] Concentration of mercury biomagnifies as it passes up the food chain from organisms on lower trophic levels to apex predators. It bioaccumulates in the tissues of larger, long-lived predatory fishes. When compared to smaller, short-lived fishes, bowfin tend to concentrate mercury at higher levels thereby making them less safe for human consumption.[14][52][53][54]


  1. ^ Crow, K. D.; Stadler, P. F.; Lynch, V. J.; Amemiya, C; Wagner, G. P. (2005). "The "Fish-Specific" Hox Cluster Duplication is Coincident with the Origin of Teleosts". Molecular Biology and Evolution 23 (1): 121–36. doi:10.1093/molbev/msj020. PMID 16162861.  edit
  2. ^ a b IGFA. "Bowfin". International Game Fish Association. Retrieved June 4, 2014. 
  3. ^ Natural History Collections. "Subclass Actinopterygii: Relict Species of Ray-Finned Fish & Origin of Teleosts". University of Edinburgh. Retrieved June 2, 2014. 
  4. ^ "Bowfin". Net Industries, LLC. Retrieved June 2, 2014. 
  5. ^ a b Jared Handley and Jesse Fielder (2004). "The Skeletal System of the Bowfin (Amia calva)". Murray State University. 
  6. ^ a b c d e f g h Wisconsin DNR. "Bowfin Family-Amiidae". University of Wisconsin. p. 254. Retrieved June 8, 2014. 
  7. ^ a b c John Acorn (7 February 2007). Deep Alberta: Fossil Facts and Dinosaur Digs. University of Alberta. pp. 10–. ISBN 978-0-88864-481-7. 
  8. ^ Indiana Department of Fish & Wildlfife. "Bowfin (Amia calva)". Indiana Department of Natural Resources. Retrieved June 13, 2014. 
  9. ^ Lance Grande (June 14, 2013). The Lost World of Fossil Lake: Snapshots from Deep Time. University of Chicago Press. p. 178. Retrieved June 13, 2014. 
  10. ^ a b R.G. Boutilier (1990). "Control and Co-Ordination of Gas Exchange in Bimodal Breathers". Vertebrate Gas Exchange Advances in Comparative and Environmental Physiology, Volume 6, Chapter 9. Springer. pp. 279–345. Retrieved June 13, 2014. 
  11. ^ a b c d e Kenneth Stewart; Douglas Watkinson (3 May 2004). Freshwater Fishes of Manitoba. Univ. of Manitoba Press. pp. 51–. ISBN 978-0-88755-374-5. 
  12. ^ Froese, Rainer, and Daniel Pauly, eds. (2009). "Amiidae" in FishBase. January 2009 version.
  13. ^ a b c d e Jay Stauffer (1 December 2007). Fishes of West Virginia. Academy of Natural Sciences. pp. 40–. ISBN 978-1-4223-1783-9. 
  14. ^ a b c d Johnathan G. Davis. "Reproductive Biology, Life History and Population Structure of a Bowfin Amia calva Population in Southeastern Louisiana, Fall 2003". Nicholls State University. Retrieved June 7, 2014. 
  15. ^ a b c d e f g University of Florida. "Bowfin". Ichthyology at the Florida Museum of Natural History. Florida Museum of Natural History. Retrieved June 11, 2014. 
  16. ^ Gene Helfman; Bruce B. Collette; Douglas E. Facey; Brian W. Bowen (3 April 2009). The Diversity of Fishes: Biology, Evolution, and Ecology. John Wiley & Sons. pp. 37–. ISBN 978-1-4443-1190-7. 
  17. ^ a b c d e f g Ken Schultz (15 December 2010). Ken Schultz's Field Guide to Freshwater Fish. John Wiley & Sons. pp. 64–. ISBN 978-1-118-03987-8. 
  18. ^ "Bowfin (Almia calva)". Indiana Department of Natural Resources. Retrieved June 13, 2014. 
  19. ^ Nelson, Joseph S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0-471-25031-7
  20. ^ "Northern Snakehead". Pennsylvania Fish & Boat Commission. Retrieved July 22, 2014. 
  21. ^ "Northern Snakehead Fish". New York Department of Environmental Conservation. Retrieved July 22, 2014. 
  22. ^ Michigan DNR. "Snakehead Fish". Fish Identification. Michigan Department of Natural Resources. Retrieved June 14, 2014. 
  23. ^ DNR (June 27, 2012). "Bowfin mistaken as snakeheads". Alerts and Notifications, event calendar press release. Indiana Department of Natural Resources. Retrieved June 14, 2014. 
  24. ^ Bureau of Fisheries Management. "Snakehead, Bowfin, or Burbot - Know the difference". Wisconsin Anglers Want To Know brochures. Wisconsin Dept. of Nartural Resources. Retrieved June 14, 2014. 
  25. ^ D.C. Jackson, C.G. Farmer (March 5, 1998). "AIR-BREATHING DURING ACTIVITY IN THE FISHES LEPISOSTEUS OCULATUS AND AMIA CALVA". The Journal of Experimental Biology (201): 943–948. Retrieved 8 June 2014. 
  26. ^ Hedrick MS, Jones DR (January 1999). "Control of gill ventilation and air-breathing in the bowfin amia calva". National Center for Biotechnology Information. 
  27. ^ David J. McKenzie, John F. Steffensen, Edwin W. Taylor and Augusto S. Abe (December 19, 2011). "The contribution of air breathing to aerobic scope and exercise performance in the banded knifefish Gymnotus carapo L.". Research Article. The Company of Biologists Ltd. pp. 1323–1330, Introduction. doi:10.1242/jeb.064543. Retrieved June 13, 2014. 
  28. ^ Water Quality Assessment Division (2005). "Canon Envirothon Water Quality Study". Louisiana Department of Environmental Quality. p. 18. Retrieved June 13, 2014. 
  29. ^ a b c d e f g h i Stephen T. Ross (2001). The Inland Fishes of Mississippi. Univ. Press of Mississippi. pp. 94–. ISBN 978-1-57806-246-1. 
  30. ^ Wilfred T. Neill (1950). Copeia, 1950, An estivating bowfin. American Society of Ichthyologists and Herpetologists. p. 240. 
  31. ^ William F. Loftus, James A. Kushlan (1987). "Freshwater fishes of southern Florida". Florida State Museum Biological Sciences. p. 183, Volume 31, No. 4. 
  32. ^ Wolfgang J. Plunk, Peter B. Bayley, Richard E. Sparks (1989). The Flood Pulse Concept in River-Floodplain Systems (Report). University of Florida. p. 117, 8-pdf.
  33. ^ McKenzie, D. J.; Randall, D. J. (1990). "Does Amia calva aestivate?". Fish Physiology and Biochemistry 8 (2): 147. doi:10.1007/BF00004442. PMID 24221948.  edit
  34. ^ Gene Helfman, Bruce B. Collette, Douglas E. Facey, Brian W. Bowen (2009). The Diversity of Fishes: Biology, Evolution, and Ecology. Wiley-Blackwell. p. 257, Chapter 13. 
  35. ^ a b c d e Rudolph John Miller; Henry W. Robison (2004). Fishes of Oklahoma. University of Oklahoma Press. pp. 58–. ISBN 978-0-8061-3610-3. 
  36. ^ a b c d e f g Freshwater Fishes of South Carolina. Univ of South Carolina Press. 2009. pp. 80–. ISBN 978-1-57003-680-4. 
  37. ^ a b Joshua Laerm; B. J. Freeman (January 2008). Fishes of the Okefenokee Swamp. University of Georgia Press. pp. 37–. ISBN 978-0-8203-3135-5. 
  38. ^ a b c d e Timothy Bonner. "Amia calva - bowfin". Published literature from Texas State University - San Marcos. Fishes of Texas. Retrieved June 11, 2014. 
  39. ^ Alan Richmond. "Bowfin or Dog Fish". Amia calva, Linnaeus, 1766. University of Massachusetts Biology. Retrieved June 11, 2014. 
  40. ^ Randy Jackson, Sr. Research Associate, Cornell University. "The Bowfin: New York's Disrespected Living Fossil". New York Department of Environmental Conservation. Retrieved June 11, 2014. 
  41. ^ Adam Emerson. "Amia calva, Beaverfish (Also: Blackfish; Bonnetmouth; Cottonfish; Cypress trout)". University of Michigan, Museum of Zoology. Retrieved June 14, 2014. 
  42. ^ Animals, (1979). "Bowfins: Amiiformes - Physical Characteristics, Geographic Range, Habitat, Diet, Behavior and Reproduction, Bowfins and People, Conservation Status". Reference for the animal kingdom. Net Industries. Retrieved June 11, 2014. 
  43. ^ Berra, Tim M. (2001). Freshwater Fish Distribution. San Diego: Academic Press. ISBN 0-12-093156-7
  44. ^ Inoue JG, Miya M, Tsukamoto K, Nishida M. (January 2003). Mol Phylogenet Evol.. Academic Press. 
  45. ^ Thom Holmes (June 28, 2008). The First Vertebrate. Chelsea House Publishers. p. 144. 
  46. ^ a b Randy Jackson, Sr. Research Assoc., Cornell University. "The Bowfin,New York's Disrespected Living Fossil". New York Department of Environmental Conservation. Retrieved June 4, 2014. 
  47. ^ David A. Bourgeois (April 5, 2009). "Choupique may be a trash fish for some, treasure to others". Daily Comet. 
  48. ^ Susan Saulny (June 9, 2012). "A Roe, By Any Other Name". New York Times. 
  49. ^ John DeSantis (December 19, 2012). "Caviar Caveats: Locals concerned about bowfin numbers". TriParish Times. 
  50. ^ Christopher Scharpf (December 30, 2013). "Bowfin: North America's Freshwater Thug". USF&WS. 
  51. ^ EPA. "Fish Consumption Advisories". Environmental Protection Agency. Retrieved June 6, 2014. 
  52. ^ NCDPHS. "What fish are safe to eat?". North Carolina Division of Public Health. Retrieved June 4, 2014. 
  53. ^ Sean Rafferty, PA Sea Grant (January 22, 2003). "Fish Tumors Related to Great Lakes Areas of Concern". PA Dept. Environmental Protection, U.S. EPA Region III, PA Sea Grant. 
  54. ^ "Pearl River and Yockanookany River, Phase One, Total Maximum Daily Load for Mercury". Mississippi Dept. of Environmental Quality, TMDL/WLA Section. November 2003. p. 7, sect 2.1.2, Mercury Transport and Transformations, 2nd para. 

Further reading[edit]

  • Catherine A. McCormick. 1981. Central Projects of the lateral line and eight nerves in the bowfin,Amia Calva. The Journal of Comparative Neurology 197:1-15.
  • J.M. Conlon, J.H. Youson, and J. Whittaker. 1991. Structure and receptor-binding activity of insulin from a holostean fish, the bowfin:Amia Calva. Biochem J. 276:261-264.
  • T. M. Nguyen, T. P. Mommsen, S. M. Mims, and J. M. Conlon. 1994. Characterization of insulins and proglucagon-derived peptides from a phylogenetically ancient fish, the paddlefish: Polyodon spathula. Biochem J. 300(Pt 2): 339–345.
  • J. M. Conlon, J. H. Youson, and T. P. Mommsen. 1993. Structure and biological activity of glucagon and glucagon-like peptide from a primitive bony fish, the bowfin: Amia calva. Biochem J. 295(Pt 3): 857–861.
  • Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology 364: p.560. Retrieved 2011-05-17. 

External links[edit]