Least darters are very small, olive green perch that have 6 to 12 black blotches along their back. These dark spots help camouflage them from predators. They have rough scales and dark lines coming out from their eyes. They look like they are a lot longer than they are wide. Females are a little bit bigger than males. Females in the breeding season have yellow fins. Males in the breeding season have orange or red spots on the fins along their back. Males also turn red or orange on their pelvic fins. ("Least darter (Etheostoma microperca)", 2003; "Perches", 2012; "Least Darter", 2012; Hatch, 1986; Johnson and Hatch, 2001; Jordan and Gilbert, October 2010; Jordann and Gilbert, 2012)
Least darters live in the northern United States and in southern Ontario, Canada. They live in the Great Lakes and rivers that drain into the Mississippi River. The are found in western Ohio, Illinois and Indiana, and in certain parts of Oklahoma, Arkansas, Kansas and Missouri. ("Least darter (Etheostoma microperca)", 2003; Jordan and Gilbert, October 2010; Jordann and Gilbert, 2012; "Etheostoma microperca", February 2009)
Least darters live in slow-moving freshwater streams, ponds, and rivers that have sandy bottoms and lots of plants. They prefer sediments and silt in the water. This kind of habitat helps them stay away from predators and has safe places for them to lay their eggs. To lay their eggs, they choose a shallow pool. Later, they go back to deeper water. ("Least darter (Etheostoma microperca)", 2003; Hatch, 1986; Johnson and Hatch, 2001)
Least darters grow to be about 29 mm long after the first year and 34 mm long by their second summer. By the time they are fully grown, females are usually bigger than males. (Hatch, 1986)
Least darters breed in the spring or summer depending on where they live. In the southern United States, the breeding season begins in February. Farther north, it begins in late May and continues into late July. Males find a territory of 1 or 2 plants that is about 5 or 10 cm big. In the wild, territories can be up to 30 cm in size. Males chase rival fish away from their territory by head-to-tail nudging. Females come near the plants in the male's territory. Females release their eggs and then males release reproductive cells to fertilize them. Females have more than one mate. ("Least darter (Etheostoma microperca)", 2003; Cordes and Page, 1980; Hatch, 1986; "Etheostoma microperca", February 2009)
Least darters change colors the breeding season. Their skins get darker green with black blotches. Their fin in the back of their belly turns bright orange. Their green color gets darker and so do their black blotches. The fins on their back and tail turn white with gray bands. ("Least darter (Etheostoma microperca)", 2003; Cordes and Page, 1980; Hatch, 1986; "Etheostoma microperca", February 2009)
Least darters are able to breed in the first spring after they hatch. Males choose a territory that they defend from other males. Males court females with a swimming ritual. Females attach their eggs to a rock or plant and then leave the male's territory. Females in their first year have small, white eggs. Males usually guard the eggs in the territory until they hatch, but sometimes leave and try to breed with another female. (Cordes and Page, 1980; Dalton, 1990; Hatch, 1986; Paine, et al., 1982)
Most least darters only 13 to 14 months. The longest a least darter lived in the wild was 3 years. Least darters in captivity live longer because it is a lot easier to get energy to survive. (Hatch, 1986)
In the spring between March and May, least darters travel from deeper streams to shallower streams with weeds. They are territorial, and males sometimes get aggressive in the breeding season. ("Least Darter", 2012; Hatch, 1986; Johnson and Hatch, 2001)
Like other perch, least darters can see, hear, and feel vibrations in the water. Females use their sense of sight to choose males during the breeding season. Brighter-colored males have a better chance of getting a mate. ("Least darter-Etheostoma microperca", 2004; "Least darter (Etheostoma microperca)", 2003; "White Perch", 2002)
Least darters are both predators and prey. They are not known to get infected with any parasites.
Least darters do not have any known negative impacts on humans.
Least darters do not provide any known economic benefits for humans. (Hatch, 1986)
Least darters are not officially listed as threatened or endangered, but the number of them is decreasing. They are threatened by loss of habitat, pollution, invasive species, pesticides used in farming, and cutting down trees. Minnesota and Arkansas are starting to try to protect them. Least darters are at risk because they are small fishes and groups of them live far apart from each other. ("Least darter-Etheostoma microperca", 2004; "Targeting and facilitating conservation efforts for two Arkansas darters: Etheostoma cragini and E. microperca.", 2008)
Beth Keskey (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Catherine Kent (editor), Special Projects.
NatureServe Explorer. February 2009. Etheostoma microperca. An Online Encyclopedia of Life, 7.1 Edition. NatureServe. Accessed February 08, 2012 at http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Etheostoma%20microperca.
Department of Natural Resources. 2012. "Least Darter" (On-line). ODNR Division of Wildlife. Accessed March 04, 2012 at http://dnr.state.oh.us/Home/species_a_to_z/leastdarter/tabid/21861/Default.aspx.
ARKive. 2003. "Least darter (Etheostoma microperca)" (On-line). ARKive Imagines of Life on Earth. Accessed February 08, 2012 at http://www.arkive.org/least-darter/etheostoma-microperca/#text=Description.
2004. "Least darter-Etheostoma microperca" (On-line). Iowa Fish Atlas. Accessed April 03, 2012 at http://maps.gis.iastate.edu/iris/fishatlas/IA168411.html.
Commonwealth of Pennsylvania. 2012. "Perches" (On-line). Gallery of Pennsylvania Fishes. Accessed April 03, 2012 at http://fishandboat.com/pafish/fishhtms/chap23.htm.
2008. "Targeting and facilitating conservation efforts for two Arkansas darters: Etheostoma cragini and E. microperca." (On-line). Accessed April 03, 2012 at http://www.wildlifearkansas.com/proposals/2008Preproposals/Arkansas%20Darter%20and%20Least%20Darter%20conservation.pdf.
University of Michigan. 2002. "White Perch" (On-line). Critter Catalogue. Accessed March 04, 2012 at http://www.biokids.umich.edu/critters/Morone_americana/.
Cordes, L., L. Page. 1980. Feeding chronology and diet composition of two darters (Percidae) in the Iroquois River System, Illinois. American Midland Naturalist, 104: 202-204.
Dalton, K. 1990. Status of the Least Darter, Etheostoma microperca , in Canada. Canadian Field-Naturalist, 104: 53-58.
Hatch, J. 1986. Life History of the Least Darter in Dinner Creek, Becker County, Minnesota. Conservation Biology Research Grants Program. Accessed February 08, 2012 at http://files.dnr.state.mn.us/eco/nongame/projects/consgrant_reports/1986/1986_hatch2.pdf.
Johnson, J., J. Hatch. 2001. Life History of the Least Darter Etheostoma microperca at the Northwestern Limits of its Range. American Midland Naturalist, 125: 87-103. Accessed February 08, 2012 at http://www.jstor.org/stable/10.2307/2426372.
Jordan, , Gilbert. October 2010. "Etheostoma microperca" (On-line). Accessed February 08, 2011 at http://www.fishbase.org/summary/speciessummary.php?id=3441.
Jordann, , Gilbert. 2012. "Etheostoma microperca" (On-line). Minnesota Department of Natural Resources. Accessed March 26, 2012 at http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=AFCQC02450.
Kelly, N., T. Near, S. Alonzo. May 2012. Diversification of egg-deposition behaviours and the evolution of male parental care in darters (Teleostei: Percidae: Etheostomatinae). Journal of Evolutionary Biology, 25/5: 836-846.
Paine, M., J. Dodson, G. Power. 1982. Habitat and food resource partitioning among four species of darters (Percidae: Etheostoma ) in a southern Ontario stream. Canadian Journal of Zoology, 60: 1635-1641.