San Marcos Gambusia (Gambusia georgei)

Picture of San Marcos Gambusia (Gambusia georgei)

TPWD © Educational use permitted.

Texas Status
U.S. Status
Endangered, Listed in 1980
Similar in appearance to the mosquitofish (Gambusia affinis), the San Marcos gambusia has a prominent dark stripe along the upper edges of the dorsal fin. It reaches about one inch in length.
Life History
The San Marcos gambusia thrives on a diet of small invertebrates. It gives birth to live young.
The San Marcos gambusia lives in clear spring water coming from the headwaters of the San Marcos River.
This species is found only in the San Marcos River, Hays County, Texas.
The genus Gambusia contains more than 30 species. The San Marcos gambusia was last collected in the wild in 1983. It is one of the rarest animals of the San Marcos River, and may already be extinct. Reduced flow of water from the springs and water pollution from the growth of nearby cities are the major threats to the San Marcos Gambusia and other species dependent on the unique ecosystem of the San Marcos River. Introduction of non-native species is also a threat because they may destroy aquatic vegetation, prey on endangered animals, or compete with them for food.