endemic to a single state or province
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Historically this species occupied Comal (Guadalupe River system) and San Marcos springs, central Texas; it has been widely introduced in springs in the Colorado and Rio Grande (including Pecos River) drainages in western Texas (Minckley et al. 1991, Page and Burr 2011).
Length: 3 cm
Habitat and Ecology
Habitat Type: Freshwater
Comments: Habitat includes cool, clear, high-volume discharge springs near their emergence from underground limestone aquifers; this species is often in swift water (Lee et al. 1980, Page and Burr 2011).
Depth range (m): 0.5 - 0.5
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 6 - 20
Comments: Nine localities in western and central Texas were mapped by Lee et al. (1980). Formerly in two springs and spring runs; now in four more (C. Hubbs, pers. comm., 1995).
Life History and Behavior
Live bearing. May breed year-round. Gravid females "dominate" populations from late March to early June in Devil's River.
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N4 - Apparently Secure
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
Reasons: Occurs in springs in central Texas; introductions have improved the conservation status.
Abundance is ten times historical level (C. Hubbs pers. comm. 1995).
Trend over the past 10 years or three generations is uncertain but likely to be relatively stable.
Global Short Term Trend: Relatively stable (=10% change)
Comments: Trend over the past 10 years or three generations is uncertain but likely relatively stable.
Global Long Term Trend: Increase of >25%
Comments: Abundance is ten times historical level (C. Hubbs, pers. comm., 1995).
Comments: Likely secure, based on numbers and "wide" distribution (Minckley et al. 1991). No significant threats are known (C. Hubbs, pers. comm., 1995).
Names and Taxonomy
Comments: Subgenus ARTHROPHALLUS, SENILIS species group (Rauchenberger 1989). See Rauchenberger (1989) for a study of the interrelationships of the subgenera and species groups within the genus GAMBUSIA.