''Noturus hildebrandi'', also known as the least madtom, is a species of

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

. Its native range stretches from the

Obion River The Obion River system is the primary surface water Surface water is water located on top of land forming terrestrial (inland) waterbodies, and may also be referred to as ''blue water'', opposed to the seawater and waterbodies like the ocean ...

in Kentucky to the

Homochitto River The Homochitto River (pronounced "ho-muh-CHIT-uh") is a river in the U.S. State of Mississippi. It flows from its source in southwest Mississippi for about west and south, emptying into the Mississippi River between Natchez and Woodville. Acco ...

in Mississippi.

Description

The least madtom is a small slender-bodied fish with a flat head. It measures up to 6.9 centimeters in length. The

adipose fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...

is either clear or white; however, populations in Mississippi sometimes have a dark patch on the adipose fin. Body coloration varies by geography. There are two known subspecies, ''Noturus h. hildebrandi'' and ''Noturus h. lautus. N. h. hildebrandi,'' which inhabits the Homochitto River and Bayou Pierre, has a long head and a mottled coloration. ''N.h. lautus'' lives in the Obion and surrounding rivers; this subspecies has a shorter head and four light-colored oval areas on a red-brown to black back. Males and females are identical in appearance. Most live about 12 to 15 months, dying shortly after reproducing.

Habitat

The least madtom inhabits sandy

riffle A riffle is a shallow landform in a flowing channel. Colloquially, it is a shallow place in a river where water flows quickly past rocks. However, in geology a riffle has specific characteristics. Topographic, sedimentary and hydraulic indica ...

s, mixed rock riffles, creeks, pools, and small rivers. It is commonly found in shallow areas containing submerged logs, sticks, leaves, and other debris.

Reproduction

The least madtom's spawning season lasts from June through August. During this time the males increase in size. The females spawn during their second summer. To prepare for spawning, adults take shelter, either singly or in pairs, under stones, shells, or in debris. An average of 19 orange

oocyte An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ...

s are laid in these areas. Both parents guard the nest as the eggs develop. Eggs hatch within 8 to 9 days. Yolk resorption takes about 9 to 10 days after hatching.

Diet

The least madtom's diet consists of 16 different

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

Midge A midge is any small fly, including species in several families of non-mosquito Nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. Some mid ...

s make up the majority of their diet, followed by

caddisfly The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...

larva. Crustaceans are consumed only in late winter and early spring. The size of prey is proportional to body size.

References

{{Taxonbar, from=Q3753214 Noturus Freshwater fish of the United States Fish of the Eastern United States Endemic fauna of the United States Endemic fauna of Tennessee Fauna of the Southeastern United States Fish described in 1950