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

catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...

. Its native range stretches from the

Obion River The Obion River system is the primary surface water drainage system of northwestern Tennessee, United States. Description The Obion has four major forks, the North Fork, Middle Fork, South Fork and Rutherford Fork (which is named after Hen ...

in Kentucky to the Homochitto River in Mississippi.

Description

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

adipose fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only b ...

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 ger ...

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 animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

taxa In biology, a taxon (back-formation from ''taxonomy''; : 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 name and ...

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

s make up the majority of their diet, followed by

caddisfly The caddisflies (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 basis ...

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 fish of the United States Fauna of the Southeastern United States Fish described in 1950