The northern studfish (''Fundulus catenatus'') is among the largest of the killifish and is native to the southcentral United States. Fundulus catenatus 289053625

Description

The mean length for adults is with a maximum size of . Northern studfish are

sexually dimorphic Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

. Males have horizontal rows of bright orange spots on light blue background and a bright orange tail margin followed by a nearly black band during breeding season. Females are more cryptic colored in shades of beige and olive. Their body shape is elongate and narrow and lacks a lateral line. Northern studfish have spineless fins and both the anal and

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

s are large.

Geographic distribution

Upper East Fork White River system,

Indiana Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the s ...

; upper

Salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

and

Kentucky River The Kentucky River is a tributary of the Ohio River in Kentucky, United States. The river and its tributaries drain much of eastern and central Kentucky, passing through the Eastern Coalfield, the Cumberland Mountains, and the Bluegrass re ...

drainages,

Kentucky Kentucky (, ), officially the Commonwealth of Kentucky, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Illinois, Indiana, and Ohio to the north, West Virginia to the ...

; upper

Green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a com ...

middle, and lower

Cumberland Cumberland ( ) is an area of North West England which was historically a county. The county was bordered by Northumberland to the north-east, County Durham to the east, Westmorland to the south-east, Lancashire to the south, and the Scottish ...

, and

Tennessee River The Tennessee River is a long river located in the Southern United States, southeastern United States in the Tennessee Valley. Flowing through the states of Tennessee, Alabama, Mississippi, and Kentucky, it begins at the confluence of Fren ...

drainages,

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

, Kentucky,

Tennessee Tennessee (, ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Kentucky to the north, Virginia to the northeast, North Carolina t ...

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

, and

Mississippi Mississippi ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South regions of the United States. It borders Tennessee to the north, Alabama to the east, the Gulf of Mexico to the south, Louisiana to the s ...

; West of

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

(primarily Ozark and Ouachita uplands) in central and southern

Missouri Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...

, southeastern

Kansas Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...

, eastern

Oklahoma Oklahoma ( ; Choctaw language, Choctaw: , ) is a landlocked U.S. state, state in the South Central United States, South Central region of the United States. It borders Texas to the south and west, Kansas to the north, Missouri to the northea ...

and southern

Arkansas Arkansas ( ) is a landlocked state in the West South Central region of the Southern United States. It borders Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, Texas to the southwest, and Oklahoma ...

; southwestern Mississippi in the Mississippi drainage ( Coles Creek, Homochitto River, and

Buffalo Bayou Buffalo Bayou is a slow-moving river which flows through Houston in Harris County, Texas. Formed 18,000 years ago, it has its source in the prairie surrounding Katy, Texas, Katy, Fort Bend County, Texas, Fort Bend County, and flows approximately ...

) and Gulf Slope drainage (

Amite River The Amite River () is a tributary of Lake Maurepas in Mississippi and Louisiana in the United States. It is about long. It starts as two forks in southwestern Mississippi and flows south through Louisiana, passing Greater Baton Rouge, Louisia ...

and

Pearl River The Pearl River (, or ) is an extensive river system in southern China. "Pearl River" is often also used as a catch-all for the watersheds of the Pearl tributaries within Guangdong, specifically the Xi ('west'), Bei ('north'), and Dong ( ...

). Live bait buckets and releases of aquarium pets have caused expansion of the native distribution of this species.

Ecology

Northern studfish are egg layers and prefer clear, shallow pools and rocky creeks that have a mixed sand/gravel

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

and constant, sluggish flow. Males do not build nests but they do stake out a territory and defend it. Females lay a clutch of 28 to 245 eggs and give no parental care to their young. Their main diet consists of insects which they skim from the surface of the water but they have also been known to consume snails.

Management

Causes for declining numbers in some areas range from introduction of aggressive non native fish species like the mosquitofish (''Gambusia'' spp.)Sutton, Trent M., RA Zeiber and BE Fisher. "Agonistic Behavioral Interactions Between Introduced Western Mosquitofish and Native Topminnows." ''Journal of Freshwater Ecology.'' to

anthropogenic Anthropogenic ("human" + "generating") is an adjective that may refer to: * Anthropogeny, the study of the origins of humanity Anthropogenic may also refer to things that have been generated by humans, as follows: * Human impact on the enviro ...

loss of water quality and movement from habitat alteration.Warren, M.L. Jr. and M.G. Pardew. "Road Crossings as Barriers to Small Stream Fish Movements." ''American Fisheries Society'' 127:637-644. Northern studfish require clear water so control of sediment is integral. Current management practices are to plant riparian zones in order to stabilize the streambanks and control run off from agriculture and construction projects.

Description

Geographic distribution

Ecology

Management

References

Further reading