Least darter (Etheostoma microperca)

GenusEtheostoma (1)
SizeLength: up to 4.4 cm (2)

The least darter is classified as Least Concern (LC) on the IUCN Red List (1).

The least darter (Etheostoma microperca) is a small, robust freshwater fish found in North America (3). It has a deep, flattened body, a rounded snout, large eyes and an unscaled breast (4). It is olive-brown above and white to yellow on the underside. There is a series of dark blotches along the sides, a distinct black line runs through the snout and eyes, and there is a dark teardrop under the eyes. There is also black spotting on the underside (5). 

During the breeding season, the male least darter becomes dark green with iridescent green scales and the dark blotches turn black. The caudal fin and the second dorsal fin become milky white with charcoal grey bands, and the pelvic and anal fins become enlarged and bright orange (5).

Occurring in the Great Lakes and Mississippi River basins, the least darter is found from eastern Ontario and Minessota, south to Ohio, Indiana, and Illionis, with isolated populations in Missouri, Kansas, Arkansas and Oklahoma (2) (6).

The least darter most often inhabits quiet, vegetated lakes, headwaters, creeks and small rivers, where it is usually found over mud and sand. This species also occurs in streams, springs and ponds, and it spawns in shallow, weedy areas (2) (6).

Very little is known about the biology and behaviour of the least darter. It spawns from February to late July, with the timing of breeding varying across its range. Females are thought to produce at least three clutches of eggs each breeding season (6), and each egg is deposited individually on vegetation (3). The larvae hatch in about six days and reach maturity at a year old. The least darter is thought to live to around 20 months (6). 

The least darter feeds on a variety of aquatic invertebrates, with copepods being a particularly important part of its diet (2).

No major threats to the least darter are known at present (1).

The least darter has not been the target of any known conservation measures, and is currently of relatively low conservation concern (1).

Find out more about the least darter:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. IUCN Red List (August, 2013)
  2. FishBase - Least darter (July, 2011)
  3. Smith, P.W. (2002) The Fishes of Illinois. University of Illinois Press, Champaign, Illinois.
  4. Simon, T.P. (2011) Fishes of Indiana: A Field Guide. Indiana University Press, Indiana.
  5. Goldstein, R.J., Harper, R.W. and Edwards, R. (2000) American Aquarium Fishes. Texas A&M University Press, Texas.
  6. NatureServe Explorer - Least darter (July, 2011)