The Bowfin (Amia calva) and the Northern Snakehead (Channa argus) are often confused due to their similar long, cylindrical body shapes and predatory habits in North American freshwaters. However, they are two entirely different species belonging to distinct taxonomic orders, separated by over 100 million years of evolution. Distinguishing them is crucial because the Bowfin is a native, ancient fish, while the Snakehead is a non-native, invasive species subject to strict regulations concerning its capture and handling.
Distinguishing Physical Traits
The dorsal fin, running along the back, offers a clear distinction: the Bowfin possesses a single, very long, flowing dorsal fin that extends more than half the length of its back, often nearly reaching the tail base. In contrast, the Northern Snakehead’s dorsal fin is also long but looks less continuous and is typically completely separated from the caudal (tail) fin.
The anal fin, located on the underside of the fish, provides another immediate identifier. The Bowfin has a relatively short anal fin, positioned further back, leaving a significant gap between it and the tail. The Northern Snakehead has a much longer anal fin that runs nearly half the length of the body, creating a continuous, skirt-like appearance.
A prominent feature on the Bowfin, particularly in males and juveniles, is a distinct black eyespot (ocellus) located near the base of the tail fin, often surrounded by a yellow or orange ring. This spot is generally absent on the Northern Snakehead, which instead often displays a blotchy, python-like pattern along its flanks.
The structure of the head also differs significantly. The Bowfin is the only freshwater fish in North America with a single, bony gular plate located underneath the jaw between the two sides of the lower jawbone. The Northern Snakehead lacks this gular plate entirely, and its head is typically flatter and covered in enlarged scales, giving it a more reptilian appearance.
Geographic Origin and Range
The Bowfin (Amia calva) is a native of North America, recognized as a “living fossil” and the sole surviving member of an ancient lineage dating back to the Jurassic period. Its natural range encompasses the eastern half of the continent, including the Great Lakes region, the Mississippi River basin, and the Atlantic and Gulf coastal drainages.
The Northern Snakehead (Channa argus), conversely, is native to parts of Asia, specifically eastern China, southern Siberia, and Korea. Its presence in North American waters is the result of human introduction, primarily through the illegal release of fish from the live food fish trade or the aquarium trade. Since its first confirmed sighting in a Maryland pond in 2002, the snakehead has established invasive populations, particularly in the Mid-Atlantic states within the Chesapeake Bay watershed.
The snakehead’s ability to spread has led to its detection in various disconnected areas across the United States, including New York, Pennsylvania, and parts of the Mississippi River system, representing a threat to local fish populations.
Unique Adaptations and Legal Status
The Northern Snakehead possesses a suprabranchial organ, a specialized chamber near its gills, which allows it to breathe atmospheric oxygen, a trait known as facultative air breathing. This adaptation enables the snakehead to survive in low-oxygen, stagnant, or muddy water and remain alive out of water for short periods, facilitating limited terrestrial locomotion.
The Bowfin also has the ability to gulp air, utilizing a highly vascularized swim bladder that functions as a lung, which is why it can survive in poor water quality. However, its dependence on water is greater than the snakehead’s, and it cannot move across land to colonize new, distant habitats.
The difference in their biology results in distinct legal status. The Northern Snakehead is listed under the federal Lacey Act as an “injurious species,” making it illegal to import, possess, or transport it live across state lines without a permit. Many states require immediate destruction if a Northern Snakehead is caught, and anglers are strongly encouraged to report catches to wildlife authorities to aid in population control.
The Bowfin, as a native species, is generally classified as a sport fish subject to standard state fishing regulations, such as size and creel limits, and should be handled with care and released if not harvested.