The least darter (Etheostoma microperca) is a species of small freshwater ray‑finned fish in the family Percidae, which also includes perches, ruffes, and pikeperches. It belongs to the subfamily Etheostomatinae, commonly known as darters.
Taxonomy
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Perciformes
- Family: Percidae
- Subfamily: Etheostomatinae
- Genus: Etheostoma
- Species: E. microperca
Physical description
- Size: Typically 2.0–2.5 cm (0.8–1.0 in) in total length, making it one of the smallest darter species.
- Body: Elongated and laterally compressed, with a short, pointed snout.
- Coloration: Generally pale olive to light brown dorsally, with a series of faint, darker blotches along the lateral line; the ventral side is lighter. Sexual dimorphism is minimal, though breeding males may display subtle changes in pigment intensity.
Distribution and habitat
- Geographic range: Central United States, primarily in the Mississippi River basin and its tributaries, including parts of Illinois, Indiana, Ohio, Kentucky, Missouri, and Tennessee.
- Habitat: Prefers slow‑moving or still sections of small streams and creeks with sandy or fine gravel substrates, often among submerged vegetation, leaf litter, or woody debris. Water temperatures are usually moderate (10–20 °C; 50–68 °F).
Ecology and behavior
- Diet: Primarily microinvertebrates such as copepods, cladocerans, and insect larvae.
- Reproduction: Spawning occurs in spring. Males establish and guard small nests under rocks or among vegetation, where females deposit eggs. After fertilization, males continue to guard the nest until hatching.
- Lifespan: Typically 1–2 years in the wild.
Conservation status
- The International Union for Conservation of Nature (IUCN) lists the least darter as “Least Concern” due to its relatively wide distribution and stable populations.
- Localized threats include habitat alteration from agricultural runoff, sedimentation, channelization, and the removal of riparian vegetation. Conservation measures focus on maintaining water quality and preserving natural stream habitats.
References
- NatureServe Explorer, Etheostoma microperca species profile.
- IUCN Red List of Threatened Species, Etheostoma microperca.
- Page, L. M., & Burr, B. M. (2011). Peterson Field Guide to Freshwater Fishes of North America. Houghton Mifflin Harcourt.
