The greenthroat darter (Etheostoma lepidum) is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is found in Colorado, Guadalupe and Nueces River drainages in Texas; and in Pecos River system in New Mexico.[1]
Macrohabitat: Basically a spring-run species.[2] Mesohabitat: Scarce or absent from very eurythermal locations. Occurs in a variety of non-turbid stream habitats with substrates from bedrock to silt covered (Platania 1980). A typical riffle species occurring over gravel and rubble, especially when aquatic vegetation is present. It also lives in spring areas, sometimes in cool vegetated pools.[3] Largest populations occur in vegetated rocky riffles.[4] [5] [6] [7] Species benthic after hatching.[8]
October or November through May, with populations in stenothermal environments having a longer spawning season than those in more eurythermal environments. In the Colorado River, Texas, spawning occurs November – May;[9] in the South Concho River, Texas, spawning occurs October – May.[10] Hubbs (1985) reported marked drop in reproductive activity when water temperature was raised from 20 to 23 °C.
Eggs laid on vegetation,[11] or on the underside of rocks.
In the South Concho River, TX, eggs averaged 1.3 mm in diameter, and increased in number with female size; average number of eggs in females examined was 74, with a range of about 15–200. In aquaria, spawning was observed at approximately 15–25 °C; over a 63-day period, a pair of Etheostoma lepidum laid 13 batches of eggs; numbers of eggs laid ranged from 47 to 109, totaling 1,115. Optimal temperature for egg production apparently 20–23 °C; a female held at this temperature range was observed to produce eggs, in the laboratory environment, over a period of at least 251 days. Egg incubation success is low above 24 degrees C.[12] At 28 degrees C, eggs hatch in 4–5 days, and hatch in about 40 days at 9 °C. Hubbs (1985) noted that no difference in egg production could be correlated with daylength.