The Johnny Darter, Etheostoma nigrum, is a species of ray-finned fish that are found in shallow water throughout eastern North America. It's name comes from the Greek and Latin root words of etheo meaning to filter, stoma

Stoma

In botany, a stoma is a pore, found in the leaf and stem epidermis that is used forgas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening...

 meaning mouth, nigrum

Nigrum

Nigrum, a Latin word meaning black, may refer to:* Arctornis l-nigrum, the Black V moth, a moth species found in the Palearctic ecozone* Eleutherodactylus w-nigrum, the cualita, a frog species found in Colombia and Ecuador...

 meaning black in Latin. They are important members of their aquatic ecosystems as predators and prey do not normally cause problems or have negative effects to their habitats. Their lifespan is about three years and they reach sexual maturity at the age of a year. They are generally small, solitary fish that live in benthic habitats in freshwater and are active during the day.

Geographic distribution

The Johnny Darter is found throughout eastern North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, from Wyoming

Wyoming

Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...

 and Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

 to the Atlantic seaboard as far south as North Carolina

North Carolina

North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

. They are the most common darter in Minnesota

Minnesota

Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...

 and Ohio

Ohio

Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...

.

Size

The Johnny Darter have an average length of between 1.5 and 2.5 inches. The males are generally longer than the females where males can reach up to 3 inches and the females do not get much bigger then 2.3 inches. They weigh very little with the males weighing in at a little over 2 grams and the females weigh about 1.6 grams.

Color

These small, slender fish have brown to yellow scales, paler sides, and whitish bellies. They have no bright colors and generally just have brown or black markings on a lighter tan background. These markings are usually a series of black "w" or "x" shapes along their sides running along their lateral line

Lateral line

The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...

.

Scales and fins

On the fish, the opercles (or bony are forming the gill cover) have scales, whereas the preopercle (bone at the start of the cheek), nape, and breast are scaleless. The Johnny Darter has two dorsal fins, the first has hard rays which are called spinous rays, while the second fin is soft-rayed, which are flexible. The pectoral

Pectoral

Pectoral may refer to:* Pectoral cross, a cross worn on the chest* a decorative, usually jeweled version of a gorget* Pectoral , often iconographic with hieroglyphs* Pectoralis major muscle, commonly referred to as "pectorals" or "pecs"...

 and pelvic fins are close to each other behind the gills. The pectorals are large and fanlike and are situated on the lower sides of the fish. The pelvic fins, or ventrals, are small and round and situated in the ventral side of the fish. They have a rounded tail fin on the ventral side as well.

Habitat, diet, and predators

Johnny Darters prefer clear water with sandy and gravely bottoms. They like slow moving water, but can be found in moderately cloudy, moving water as well. They are bottom-dwellers and stay on rocks at the bottoms of small ponds and streams with their heads facing into the current. Of all the darter species, the Johnny Darter is the most tolerant of diverse conditions.
Since these darters are benthic, freshwater fish, their mouth is a subterminal where the nose is only slightly beyond the mouth and is situated in an inferior position that makes it easy for them to eat and catch their food. They eat lots of different things, but as young fish, they tend to eat copepods, or small crustaceans, and waterfleas. As they grow, the fish start eating larger waterfleas, differing types of larvae including midge

Midge

A midge is a very small, two-winged flying insect. "Midge" may also refer to:-Real:* Midge Costanza , American politician* Mildred Gillars , aka "Midge", American broadcaster of Nazi propaganda during World War II...

, mayfly

Mayfly

Mayflies are insects which belong to the Order Ephemeroptera . They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies...

, and caddisfly, and they also eat the occasional sideswimmer.
These darters are generally eaten by predatory fish in their regular habitat. These predators are fish like burbot, lake trout, smallmouth bass, walleyes, and yellow perch.

Breeding

The spawning season for Johnny Darters is all of May and most of June when the water temperatures are between 12 and 24°C. Males arrive first to establish territories throughout the pond, lake, or stream. Spawning occurs throughout the shallow water or in pools and slow runs where there are large rocks, logs, cans, shells, or other debris. When a female approaches the nest, the male darts at her and chases her out of the territory. However, when she approaches the nest upside down and tries to enter, the male will accept her. They then both turn upside down and the female will lay between 30 and 200 eggs on the underside of the debris. Johnny Darters are not monogamous and the female and male will spawn with other fish. A single nest may hold up to 1000 developing eggs. The male will guard the nest and keep them oxygenated and will eat the ones that develop fungus until the embryos hatch which is about 6-10 days.

Conservation status

These fish are not considered threatened throughout most of their range. They are considered vulnerable only in these following states: Arkansas, Kentucky, Oklahoma, Kansas, and Nebraska. In Minnesota, they have no special conservation status, but are protected by state law.