The Texas shiner (Notropis amabilis) is a species of ray-finned fish in the genus Notropis. It is found in the Colorado River to Rio Grande drainage from Texas and northeastern Mexico and the Rio Salado and Rio San Juan systems in Mexico to the lower Pecos River in Texas.
Habitat associations
Macrohabitat of the Texas shiner is typically springs and headwater tributaries, where may be very common; sometimes limited number occurring in larger streams. Collections from the Blanco River (Texas) and its tributaries found N. amabilis generally associated with flowing pools, deep runs, avoiding shallow high-velocity riffles and lentic backwater areas; abundant in deep pools and silt substrates, in fall; deeper pools and runs in fall and winter. Clear waters with substrate usually sand, gravel and rubble. Often found in moderately large schools in streams with moderately fast currents; can be found in the upstream ends of pools below riffle areas, in the swiftly moving waters along gravel bars and in moderately flowing pools; commonly found in areas below lower water dams and road crossings where turbulent water flows. Where sympatric with Cyprinella lutrensis and C. venusta, N. amabilis usually selects areas having a greater current velocity than the other two species and also tends to maintain school integrity to a greater extent than do the other two species. N. amabilis is rarely found in upstream portions of tributary creeks and is common in streams with significant spring flow components. N. amabilis is dependent upon currents; most often abundant in swift water areas, often swimming near the surface in eddies created by upstream obstructions and in dense schools in swift moving water. In the Devils River, Texas, taken pre-flood in habitats intermediate between channels and pools, shifting into riffles and riffle-like habitats after the flood; study indicated species adaptation to a flood-prone existence presumably typical of a desert stream.
Biology
Spawning season
In Texas, February through September. Collection of specimens, in Texas, less than 20 mm (0.79 in) SL from mid-April to mid-December, suggests spawning begins in approximately late March and continues through approximately mid-November. In Mexico, N. amabilis evidently spawns over a protracted period from early spring into summer.
Fecundity
Oocyte diameters exhibited a trimodal distribution suggesting development of multiple cohorts throughout the spawning season. In October mature ovaries present in three of fourteen females collected; all ovaries classified as mature or resting in individuals collected in November and December. As early as January, 24% of females collected contained developing ovaries; mature ovaries first appeared in February in 17% of females; in April, 75% of females contained mature ovaries; May–July, mature ovaries found in 25-31% of females; reproduction peaked again in August and September when 86% and 71% of females, respectively, contained mature ovaries. Clutch size ranged from 102 to 286 with a mean (±SD) of 174.5 (62.2;).
Food Habits
Gut contents suggest species is an invertivore drift predator (Goldstein and Simon 1999) feeding primarily in the water column on aquatic insects. Common food items were aquatic insects (71%) and algae (61%); among aquatic insects, mayflies were most abundant (31% of insects), caddisflies (26%), flies/midges (22%), beatles (12%), and moths/butterflies (4%); terrestrial insects found in 6% of guts, comprising 5% of all insect taxa identified; sediment and detritus found in 13% of Notropis amabilis examined. In Devil's River, Texas, observed feeding near the surface. The few specimens collected contained terrestrial insects during the summer; no other information about the food habits is known.