The Clear Creek gambusia (''Gambusia heterochir'') is a species of fish in the family Poeciliidae endemic to the United States, particularly Menard County, Texas.

Habitat and biology

The Clear Creek gambusia inhabits the headwaters of Clear Creek which are derived from springs with clear, acidic water and having a constant temperature. It occurs in area where there is a growth of '' Ceratophyllum'', an aquatic plant, which is also home to this fish's main prey item, the endemic

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

'' Hyalella taxana''. The submerged vegetation also gives the gambusia cover from its predators. This is an ovoviviparous species and the young are born live. Most births occur between March and September. The fish live their entire lives in the clear spring waters of the Clear Creek tributary of the San Saba River. The fish congregate around

submerged aquatic vegetation Aquatic plants are plants that have adapted to living in aquatic environments (seawater, saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a pl ...

that provides them with food and shelter.

Conservation

The range of the Clear Creek gambusia was shrunk due to the construction of dams which allowed Western mosquitofish (''Gambusia affinis'') to displace them as the construction of the dams resulted in a greater variation in water temperatures which the mosquitofish could tolerate better than the gambusia. By 1979 the last remaining population was protected from competing congeners by being upstream from a dam, below which the waters were populated by mosquito fish. The dam had been damaged by the activities of nutria and by the growth of tree roots and hybridization between the Clear Creek gambusia and the mosquitofish was detected. The dam was repaired and the population increased and in 1985 large numbers of Clear Creek gambusia were detected below the dam. The waters below the dam now had populations of

rainwater killifish The rainwater killifish (''Lucania parva'') is a small silvery fish with yellow flashes and diamond shaped scales that is widespread from Cape Cod, Massachusetts, through to Tampico, Mexico. It is commonly found in large numbers in fresh to brac ...

(''Lucania parva''), a species not native to the area and thought to be introduced as discarded fishing bait, and it is thought that the rainwater killifishes outcompeted the mosquitofish allowing the gambusia to expand downstream of the dam. The Clear Creek gambusia was put on the United States' list of

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

in 1967.

References

Endemic fauna of Texas Gambusia Fish described in 1957 Taxa named by Clark Hubbs Menard County, Texas Taxonomy articles created by Polbot ESA endangered species {{Cyprinodontiformes-stub