Abstract
The duskytail darter, Etheostoma (Catonotus) sp., is a relict species warranting protected status. Adults and juveniles in Little River, Tennessee were most abundant in pools among cobbles and small boulders. Most males and females reached sexual maturity at 1 yr of age. Sexual dichromatism and dimorphism were conspicuous only in breeding fish. Mean clutch size was 27, and females in aquaria produced multiple clutches. Estimates of spawning frequency ranged from 5-7 clutches/yr, and fecundity from 135-189. Spawning occurred beneath slab-shaped stones from late April-June at water temperatures from 17-24 C. Females remained inverted during spawning, and males inverted for 0.5-4.0 sec at mean intervals of 3.9 min. Single-layer clusters of 23-150 eggs (mean diameter = 2.8 mm) deposited on the undersides of stones by one or more females were guarded by males until hatching (11-14 d at 18-27 C). Larvae developed prominent stellate melanophores on top of the head. Early growth was rapid, males grew faster than females, and maximum age attained was 2 yr. The estimated population of the 200 m study reach was 1023 duskytail darters. Diet consisted mainly of microcrustaceans, chironomid larvae, and heptageniid nymphs. Excessive siltation and water quality degradation threaten this population.
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