Gilt darters are medium-sized for darters, but small compared to a lot of other fish. They are about 6.35 cm long. They are dark olive on the top or back, and brightly colored bronze on their belly. They have 5 to 8 dark bands that run across their back and down their sides. They have 10 to 13 spines along their top front fin. The spines are orange on the tips and connected by dark skin. Their tail fins are much lighter or colorless. Most of their other fins are orange closer to the body and colorless at the end. Males and females look different during the breeding season. ("Minnesota Department of Natural Resources", 2011; Dickson, 2008; Eddy and Surber, 1947; Phillips, et al., 1982)
Gilt darters live North America from eastern Minnesota to western New York, south to northern Arkansas, Mississippi, Alabama, and Georgia. The area where they live is shrinking because of erosion, buildup of silt and sediment, man-made changes to the way the river flows, and pollution. ("NatureServe", 2010)
Gilt darters live in freshwater streams and rivers that are pretty clear. Their streams and rivers are 20 to 100 m wide, and flow year-round at about 0.5 to 1.2 m/sec. Gilt darters travel between different depths depending on season. In spring and early summer, they scatter and fertilize their eggs in fast-moving rocky spots of rivers. Afterwards, they move to deeper water and places with gravel bottoms, where they stay for the rest of the year. ("Minnesota Department of Natural Resources", 2011; Hatch, 2004)
Females release hundreds of yellow or orange eggs which the males fertilize. The eggs measure are 1.1 to 1.4 mm across, and get hard when they are let out into the water. Eggs hatch in 8 to 10 days, when the water temperature is about 20°C. The fish larvae are 4.0 to 4.8 mm long. They become juvenile, or young, gilt darters about 1 week later. (Hatch, 2004)
Males start to look and act different at the start of the breeding season. Their upper body turns dark blue-green and their underbellies become iridescent yellow or orange. Their sides get dark blotches and the fins turn blue on the side closer to their body. Males compete for females by marking off a territory around rocks in fast-flowing parts of the stream. They get very aggressive towards rivals. They defend their territories by chasing, tail-beating, confident body posturing, and rapid color changing. Females are pursued if they enter territory of a male. If she is interested, the female poses a certain way and communicates by touch. Females decide a location to disperse her eggs, and males fertilize them in the water. Both males and females push down on the river bottom to bury their eggs. Females mate with more than one male. (Dickson, 2008; Hatch, 2004)
Gilt darters breed once a year in the summer, when the water is 17°C or warmer. Grown-up females lay 132 to 762 eggs, and 247 on average. Eggs take about 8 to 10 days to grow into larvae. Males can mate when they are 11 to 13 months old, and females when they are 22 to 23 months old. (Hatch, 2004)
Gilt darters don't protect or care for their young after they scatter and fertilize the eggs.
Gilt darters have a lifespan of 2 to 3 years in the wild. Occasionally, some can live for 4 years. Less than 1 in 10 1-year-old gill darters lives to be 3 years old. (Hatch, 2004)
Compared to other darters, gilt darters can move around a lot in the water. They have a small gas bladder, which is a special organ that helps them move in the water. This means they swim around more than other darters. Darters get the name from using their fins to "dart" around, but gilt darters swim more than they dart. (Dickson, 2008; Phillips, et al., 1982)
Scientists don't know the normal size of home range for gilt darters. (Phillips, et al., 1982)
Like all fish, gilt darters have a sensory organ running from their head to tail called a lateral line. It helps them sense water currents and vibrations. Gilt darters use their eyes, internal ears, and lateral line to get information about their environment. (Eddy and Surber, 1947)
Gilt darters eat mostly larvae of insects that live in the water. They find their prey mostly by sight, and feed in early or in the middle of the day. There is a lot of food available from April through August, but this goes down a lot in September. Because the amount of prey available goes up and down so much, their diet changes depending on what is available. Gilt darters eat a lot of mayflies, caddisflies and other flies. They also eat midges and black fly larvae. Young gilt darters eat more caddisflies in their first 2 months than when they are adults. Before breeding, they eat more mayflies than anything else. ("NatureServe", 2010; Hatch, 2004)
The fast-flowing waters where gilt darters live are excellent safe zones from predators. All darters do a good job of avoiding predators by staying at the bottom of the river or stream. Gilt darters can also get away from a lot of predators because they can swim and change directions quickly. They are probably eaten by fish-eating fish. (Hatch, 2004; Shiels, 2011)
Gilt darters may help limit the number of insects that are pests to humans. They are likely prey for various other fish. They also play an important role in mussel reproduction as hosts for numerous species of mussel larvae called glochidia, including rabbitsfoot mussels. (Shiels, 2011)
There are no known negative impacts of gilt darters on humans. (Froese, 2010)
Gilt darters are sensitive to changes in their habitat, and often used by scientists to measure the health of their environment. ("Minnesota Department of Natural Resources", 2011)
Gilt darters live throughout the Midwest and northeastern United States. In some places where they live, they are a species of special concern because their numbers have decreased a lot in the past 50 years. When humans build dams, sediment and silt builds up in the rivers and they get cloudy, which buries the places where they breed and makes it harder for them to see their prey. They don't have any special status from the U.S. Fish and Wildlife Service. ("Minnesota Department of Natural Resources", 2011)
The scientific name for gilt darters used in Minnesota before 1955 was Hadropterus evides. (Hatch, 2004)
Steve Sveine (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, John Berini (editor), Animal Diversity Web Staff, Catherine Kent (editor), Special Projects.
2011. "Minnesota Department of Natural Resources" (On-line). Accessed April 28, 2011 at http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=AFCQC04090.
2010. "NatureServe" (On-line). Accessed April 28, 2011 at http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Percina+evides+.
Dickson, T. 2008. The Great Minnesota Fish Book. Minneapolis: The University of Minnesota Press.
Eddy, S., T. Surber. 1947. Northern Fishes. Minneapolis: The University of Minnesota Press.
Froese, R. 2010. "FishBase" (On-line). Percina evides. Accessed April 28, 2011 at http://www.fishbase.org/Summary/SpeciesSummary.php?ID=3493&AT=gilt+darter.
Hatch, J. 2004. "Gilt darter" (On-line). Accessed April 28, 2011 at http://hatch.cehd.umn.edu/research/fish/fishes/gilt_darter.html.
Phillips, G., W. Schmid, J. Underhill. 1982. Fishes of the Minnesota region. Minneapolis: The University of Minnesota Press.
Shiels, . 2011. "Pennsylvania Fish and Boat Commission" (On-line). Pennsylvania's Dynamic Darters. Accessed May 01, 2011 at http://www.fish.state.pa.us/education/catalog/darters.html.