DEMOGRAPHY, HABITAT, REPRODUCTION, AND SEXUAL DIMORPHISM OF THE CRYSTAL DARTER, CRYSTALLARIA-ASPRELLA (JORDAN), FROM SOUTH-CENTRAL ARKANSAS

Habitat and demography of the crystal darter, Crystallaria asprella, f rom the Saline River, Arkansas, were studied utilizing field samples ( March 1992 to Feb. 1993) and museum collections (1968-1991), Crystalla ria were typically collected at depths of 114-148 cm and velocities of 46-90 cm/sec. Predominant substrata were gravel, small cobble, and pa tches of sand, Crystallaria were not collected from habitats containin g mud, clay, or submerged aquatic vegetation, The reproductive season was from late Jan. through mid-April with a 1:1 sex ratio during the s eason, Clutch sizes were 106-576 mature oocytes/female and were positi vely correlated with SL (r(9) = 0.97, P < 0.01), Diameters of mature o r ripening oocytes were 1.0-1.2 mm, Long-term changes in GSI and oocyt e diameter were not apparent for the 25-year span represented by museu m collections, Both sexes attained sexual maturity before Age I, when females were 50 mm and males 61 mm SL, Sexual dimorphism was pronounce d immediately prior to and during the reproductive season, Mature male s possessed longer soft dorsal and anal fins than females, Males were usually larger than females, although maximum sizes were not appreciab ly different, Life expectancy of Crystallaria was at least two years.