San Marcos Gambusia: Texas Waterway Loss
This small fish lived only in a short section of the San Marcos River in Texas. Water extraction for agriculture and urban use reduced spring flows they depended on. Hybridization with introduced mosquitofish diluted their gene pool. Habitat modifications altered the specific conditions they required. The last confirmed sighting came in 1983. Despite its protected status, this tiny fish couldn’t withstand multiple threats to its limited habitat.