SANTIAGO: At more than 3,700 meters above sea level, the `karachi` swims happily in dense salt flat waters, but locals worry a future lithium project will endanger this extreme-environment fish.

The Orestias ascotanensis is a small ray-finned fish that grows to just 7.5 centimeters, but has adapted to the Ascotan salt flat`s high concentrations of heavy metals and variable salinity.

The salt flat also sees high solar radiation and temperature variations that reach 26 Celsius during the day and below freezing at night, according to Marco Mendez, a professor at the University of Chile who studies evolutionary biology.

Scientists at the Millennium Institute`s genome centre have been studying the fish and found genes thatallow it to resist each element of its hostile environment, from solar radiation to heavy metals to low oxygen levels. The fish has also evolved to do it quickly.

`We`ve seen how they`ve done this in a short evolutionary time because there are other variants of this fish in less hostile environments,` said Miguel Allende, director of the institute.

`They`ve taken these genes and exacerbated them.` While the fish can survive extreme environments, it still needs an environment to live in and residents say copper mining has reduced the fish population due to water extraction.

`That`s what`s hurting them, when they take the water, the fish die,` said Mauricio Anza, a local resident, who said people in the area are working to preserve the areas flora and fauna.

-Reuters