Gilt darter  (Percina evides)

The gilt darter has not yet been assessed by the IUCN.

A robust, stout-bodied fish, the gilt darter (Percina evides) is one of the most distinctive and brightly coloured freshwater fish in the United States (3). During the breeding season, the male gilt darter is particularly impressive, with bright bands of  orange-red, yellow, and vivid, iridescent blue-green markings on the head, sides, lower body and dorsal fin (3) (4).

Breeding male fish have an intense blue-black pigment on the breast, on the pelvic and dorsal fins, and at the base of the anal fin (3). The male gilt darter also develops breeding tubercles and a row of large, spiny scales along the middle of the belly (3) (4) (5). The breeding female is a more subdued orange or bronze colour, with seven or eight dark bands across the back (6).

At other times of year, the gilt darter has a dark olive upper body, becoming lighter yellow-green on the belly and sides (4) (5). Dark saddles on the back join with dark blotches on the sides to form a series of characteristic vertical bands along the body (3) (4) (5) (7). A bar of dark colour extends down from each eye (4).

The gilt darter is found only in the United States. This freshwater fish inhabits several river systems in the Mississippi River basin (2) (7), from New York and northwestern Pennsylvania to Minnesota, and south to northern Alabama and northern Arkansas. It also inhabits the Maumee River system in Indiana (2) (8).

The gilt darter previously inhabited various river drainages in Iowa, Illinois and Ohio, but it is thought that these populations have now disappeared (3) (9).

This species generally inhabits large creeks and small- to medium-sized rivers, with clear waters and moderate or fast-flowing currents, and a sand, gravel or rubble substrate (4) (7) (8) (9).

The gilt darter is often found in the deeper reaches of creeks and rivers, particularly around the middle and lower parts of rocky riffles (2) (9). It also commonly found in pools which are free of silt and other debris (4) (7).

The gilt darter is a fairly opportunistic feeder, its diet varying seasonally depending on the availability of aquatic insect larvae, such as caddisfly larvae, diptera larvae and mayfly nymphs (3) (7) (8). This species also exhibits seasonal migration between different habitats, moving from shallow riffles in the autumn to deeper channels between rubble and boulder riffles in the winter. Mature gilt darters return to the shallower riffles in the late spring and early summer to spawn (3).

The timing and duration of spawning is determined mainly by the effects of temperature and flow of the streams the gilt darter inhabits (3), although it generally begins between late April and May, depending on the location (3) (8). The gilt darter spawns over gravel and sand, in areas free from silt and other debris. It buries the eggs in the substrate, and the eggs hatch after eight to ten days (3). The female typically breeds between the ages of two and three years (8). 

During the breeding season, the male gilt darter will establish a territory around cobble or boulder stones. The male aggressively defends its territory, chasing away rival males and deterring intruders using ritualized body posturing, tail beating, fin displays and rapid colour changes (3).

Pollution and habitat alteration are the primary threats to the gilt darter (4) (7) (8) (10). The construction of dams and reservoirs in this species’ range has contributed to the loss and degradation of suitable habitat, by causing waters to become slow-moving and silty (4) (7) (8). Agricultural runoff and pollution from other activities cause declines in water quality, which further affects the gilt darter’s survival (7).

Recommended conservation measures for the gilt darter include protecting and restoring the natural river habitat of this species, as well as controlling pollution and siltation to prevent further deteriorations in water quality (4) (7).

Find out more about the gilt darter:

• FishBase - Gilt darter:
  http://www.fishbase.org/summary/Percina-evides.html