SCIENTIFIC NAME: Etheostoma caeruleum
CHARACTERISTICS: Rainbow darters are some of the most vividly colored darters found in Alabama. Breeding males have brilliant reds and blues on the sides of the body and head, while the gill membranes are typically orange. A blue marginal and a red submarginal band occur through the spiny dorsal fin. The anal fin is blue-green with a variously developed central red spot. The head is typically conical, a frenum is present in the upper lip, and the gill membranes are separate to slightly connected. Cheeks and breast are usually unscaled and the venter and opercles are scaled. The back has six to 10 dark brown, square saddles, the two most intense ones being located just in from of the behind the spiny dorsal fin. Approximately nine to 14 lateral blotches with narrow interspaces occur along the sides, with the posterior ones becoming more vertically elongated and occasionally encircling the caudal peduncle. See Storer (1845a) for original description.
ADULT SIZE: 1.6 to 2.6 in (40 to 65 mm)
DISTRIBUTION: Etheostoma caeruleum are widespread and often abundant in northern tributaries to the Tennessee River drainage in Alabama. Records are strangely absent in northeastern Alabama. The scarcity of observations from southern tributaries, except in Coastal Plain areas of the Bear Creek system, is likely attributable to the absence of suitable habitat.
HABITAT AND BIOLOGY: Adult rainbow darters inhabit fast, deep riffles over gravel, rubble, and cobble substrates while the young are typically encountered in quiet, shallow riffles and pools over sand and gravel substrates. Spawning occurs in Alabama from late April to July in shallow riffles. Winn (1958a, b) reports spawning from April to May in Michigan. Females deposit in the substrate three to seven eggs per spawning act, leaving the eggs unprotected. The diverse diet of rainbow darters consists of mayflies, midges, water mites, caddisflies, and blackflies. Variable feeding behaviors reported by Vogt and Coon (1990) may allow this species to remain common throughout its range in Alabama.
ORIGINAL DESCRIPTION: Storer described the rainbow darter in 1845.
Etheostoma means strain mouth, possibly referring to the small mouth.
Caeruleum means blue.
The copyrighted information above is from Fishes of Alabama and the Mobile Basin.