The eyetail bowfin is a stout-bodied, nearly cylindrical fish. The dorsal fin extends more than half the length of the back and has more than 45 rays. The tail fin is rounded, with the hind part of the backbone curving into the upper part of the fin. The head lacks scales. Each nostril has a barbel-like flap. The fins lack spines. Upperparts are mottled olive-green, shading to pale green on the belly. The dorsal and tail fins are dark green with darker bands or bars. The fin color of breeding males is from dull green to bright emerald green. Young fish have a black spot near the upper part of the tail base; this spot can persist in adults, particularly in males.
- Snakeheads are native to Asia and invasive in America. They resemble bowfins and can live in similar habitats. They have recently been appearing invasively in southeastern Missouri. Snakeheads, however, have an extended anal fin, and their pelvic fins are positioned near the pectoral fins and gills.
- Using DNA analysis, scientists now recognize two surviving species of bowfins in the world, both in eastern North America. Missouri's only species is Amia ocellicauda, the eyetail bowfin. The other species, Amia calva, or the ruddy bowfin, occurs along the East Coast, from Virginia to Florida, in rivers draining to the Atlantic Ocean; in the peninsula of Florida; and along the northern Gulf of Mexico from the Pearl River in Louisiana and Mississippi east through much of Alabama and Georgia to Florida. The ruddy bowfin is reddish brown (though breeding males may have slightly green fins), has only a weakly or moderately defined eyespot at the base of the tail, and has a few more teeth than the eyetail bowfin. Also, the ruddy bowfin has a slightly more elongated interopercle bone (that's a bone that makes up part of the operculum, or gill cover). (Missouri's eyetail bowfin has a less elongated interopercle bone.)
Adult length: 15–27 inches; weight: 1–5 pounds.
In Missouri, most abundant in the Mississippi Lowlands, though it occurs along the entire length of the Mississippi River. Also stocked in private lakes.
The North American range includes the upper and lower Mississippi River basins, the Ohio River basin, the Great Lakes basin, the St. Lawrence River system (including Lake Champlain), and the Connecticut River system. The southwestern extent of the range includes the Lake Pontchartrain system and west into several Texas rivers that drain into the Gulf of Mexico.
Habitat and Conservation
Bowfins occur in a variety of habitats but tend to avoid those with swift current or excessively turbid waters. In the Mississippi Lowlands, the eyetail bowfin is found in a variety of habitats ranging from swamps to ditches to pools of sluggish streams. Along the Mississippi River, it is more often found in backwaters and oxbows than in the main channel. In our state, the eyetail bowfin prefers the swampy, sluggish waters of the Bootheel, so the health of bowfin populations depends on our maintenance of what's left of those swampy habitats.
Hiding by day in deeper water, bowfins venture into shallow water to feed at night. They surface occasionally to renew the supply of air in the swim bladder, which functions something like a lung.
The young feed primarily on microcrustaceans and aquatic insects. Adults eat fish, crayfish, insects, worms, and frogs. Gizzard shad are a favorite item, followed by golden shiner, bullheads, and sunfish.
Until 2022, scientists assumed there was only one surviving species in the bowfin family. That one species, they believed, had a wide distribution in the eastern North America, and it was long known simply as the "bowfin," Amia calva. In 2022, scientists determined that bowfins in the Mississippi and Ohio river drainages, the Great Lakes, and eastern Texas, are a separate species, Amia ocellicauda, the eyetail bowfin. Meanwhile, the bowfins along the East Coast from Virginia to Florida, and in much of Georgia, Alabama, and Mississippi, should remain as A. calva; that species is now called the ruddy bowfin.
Further genetic and taxonomic research might yet reveal additional "hidden" species of bowfins in North America.
The two species of bowfins are the only living species remaining in their family. Their closest relatives appear as fossils that lived 180 million years ago.
The two species of bowfins apparently diverged from one another during the Plio-Pleistocene, a time when glaciers had advanced into the Northern Hemisphere .
Spawning lasts from April into early June. Males build nests in shallow, weedy sites, and they guard the eggs and fry. When the fry are ready to leave the nest, they travel in a swarm with the male. This schooling behavior lasts until the young are about 4 inches long, when they go their separate ways.
Generally classed as a poor food fish, and often held in contempt by many anglers, the bowfin still has a place in sport fishing. Though it is not the most spectacular fighter, it has strength and endurance. When cleaned and prepared properly, bowfin meat can be tasty.
In the past, bowfins were believed to harm the populations of sport fish, but research has disproven that idea. Bowfins play an important role in balanced ecosystems.
Invasive snakehead fish, which somewhat resemble bowfins, have attracted a lot of attention as an unwanted, voracious, sinister-looking fish; experts are concerned that people might confuse these species and unfairly persecute our native bowfishes out of fear and ignorance.
Bowfins are increasingly vulnerable to overfishing, as their roe are becoming more valuable as an alternative source of caviar. Global caviar fisheries for other species, such as sturgeons, have waned as fishing regulations are imposed on those declining and disappearing species; thus bowfin caviar has been increasing in value. Caviar harvesting can be devastating to fish populations, since to obtain the best caviar, gravid females must be harvested just a few weeks before spawning. Removing females from the wild before they can reproduce greatly reduces the population's annual renewal and can cause local extirpations. Experts have been recommending that states start considering regulations on bowfin harvest during spawning time, before their populations begin to decline. Bowfins are starting to be be aquafarmed, notably in Louisiana, for their roe (processed into what one company calls "Cajun Caviar") and for their meat.
Like many fish, a bowfin begins life as an egg and small fry, vulnerable to predation. As it grows, however, it becomes a predator of fish and crayfish smaller than itself.
The eyetail bowfin is one of several fishes that host the glochidia (larval stage) of a species of freshwater mussel called the washboard (Megalonaias nervosa). As with other mussel glochidia, these tiny clam-shaped larvae attach, for a time, to the gills of the fish but usually do not harm their hosts. The washboard is a mussel of large and medium rivers, and its North American range mostly corresponds with the range of the eyetail bowfin.