The sicklefin chub (Macrhybopsis meeki) is a species of ray-finned minnow fish in the family Cyprinidae. It is found only in the United States. It is one of the 324 fish species found in Tennessee, and is a species of concern in the Charles M. Russell National Wildlife Refuge in Montana.^[2]

Quick Facts Conservation status, Scientific classification ...

Sicklefin chub
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cypriniformes
Family:	Cyprinidae
Genus:	Macrhybopsis
Species:	M. meeki
Binomial name
Macrhybopsis meeki (D. S. Jordan & Evermann, 1896)
Synonyms
Hybopsis meeki Jordan & Evermann, 1896

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The type species was collected in the Missouri River near St. Louis, Missouri, and described by David Starr Jordan and Barton Warren Evermann in 1896.^[3] They named it Hybopsis meeki.^[3] The name meeki is in honor of Seth Eugene Meek, a noted American fish biologist.^[4] In 1908, Stephen Alfred Forbes and Robert Earl Richardson suggested the binomial name Platygobio gracilis based on a specimen collected in Illinois, but this is clearly the same species described by Jordan and Evermann.^[3]

The sicklefin chub is a small fish which can reach 4.25 inches (10.8 cm) in adulthood.^[5] The snout is round and bulbous, and overhangs the lower jaw slightly.^[4] It is fairly round and thickest around the nape (the area just in back of the head), and the body tapers significantly until it reaches the tail.^[4][5] Its head is wide and deep, flat on top, with eyes set high on the head.^[3][5] The eyes are not as high on the head as in similar species, and are sometimes covered with a flap of skin.^[4] There is a small barbel near the corner of the mouth,^[5] and small pustules on the throat.^[3] Unlike the sturgeon chub, which it closely resembles, the sicklefin chub has no "keels" (small ridge-like protrusions on its scales).^[5] This fish has silvery sides, and is light green or brown on top.^[5] The fish often exhibits dark brown or silver specks.^[5] In larger individuals, the lower lobe of the caudal fin is often black with a white edge.^[6] This fish has large, pointed, sickle-shaped fins, which gives the minnow its name.^[7] The dorsal fin originates just over or behind where the pelvic fin originates.^[5] When depressed, the first dorsal fin extends beyond the last ray. The tip of the pelvic fin can reach beyond the origin of the pelvic fin.^[7] There are eight rays in the anal fin.^[5] The chest and belly of the fish lack scales, but not the sides or tail.^[4]

Little is known about its feeding habits,^[3] although it does have teeth in its throat.^[5] Black fly pupae and other insects have been found in the stomachs of some specimens.^[8] There is some evidence that it is a bottom feeder.^[9][10] The eyes are weak and it does not see well.^[11] Its body, however, is covered with taste buds which help it locate food.^[11] There are also taste buds in the mouth, which has led to speculation that the fish sorts food orally and spits out what is not edible.^[10]

Almost nothing is known about its breeding habits,^[3] but it is an egg layer.^[9] The sicklefin chub exhibits little sexual dimorphism, and neither sex exhibits color changes during breeding.^[4] However, the male develops small tubercles on the fin rays during breeding.^[4] Breeding probably occurs in the spring,^[8][12] and the fish is thought to be quite short-lived.^[12]

The sicklefin chub lives in fast-moving rivers with sandy or fine gravel beds,^[3] but is more commonly found on sandy beds.^[8] Its range covers the entire Missouri River; the Mississippi River from the mouth of the Missouri River down to the Ohio River; and the Mississippi River in southern Mississippi and northern Louisiana.^[5] It is fairly common in the Missouri River, but rare elsewhere.^[5] It has also been reported in the lower Kansas River.^[8]

Dams have destroyed much of the sicklefin chub's habitat by slowing currents and allowing silt to precipitate from the water and cover the sand and gravel beds the fish prefers.^[13] The United States Fish and Wildlife Service (FWS) estimated in 2001 that it only inhabited about 54 percent of its former range.^[12] In 1993, the FWS considered listing the sicklefin chub as a threatened species, but declined to do so.^[14]