Life History and Ecology of the Orangefin Darter Etheostoma bellum (Pisces: Percidae)

-The life history and ecology of the orangefin darter Etheostoma bellum were studied in the Green River system, Kentucky, from 1982 to 1987. Juveniles and adults were segregated mainly by water depth, current velocity and substrate type. Use of riffle habitats varied in relation to spawning activity. Sexual maturity was typically achieved at 2 yr of age; however, maturity was attained by some early-hatched 1-yr-olds. Spawning was from late April to late June in gravel substrates of fast-flowing riffles. Large territorial males spawned over females buried in the gravel, and on one occasion cuckoldry was observed. Average number of mature ova was 41; mean diameter of mature ova was 1.58 mm. Incubation time was 7-9 days at 23 C and mean total length at hatching was 6.1 mm total length. Males grew more rapidly and attained a larger size than females; maximum longevity was ca. 36 mo. Sex ratio of males to females was 1.05:1.00. Mean density was 0.5 fish/M2 but varied seasonally. Juveniles and adults ate mainly dipteran larvae, ephemeropterans and hydracarinians but selectivity of food items varied seasonally. Diel feeding patterns were bimodal and crepuscular in summer with peak activities at 1800 h and 2400 h.