Endangered Sonoyta pupfish find refuge in Arizona's Biosphere 2

The rare Sonoyta pupfish were introduced into a desert river habitat inside the huge Biosphere 2 structure near Tucson.

The dish are native to Quitobaquito Springs near the Arizona-Mexico border, but their numbers have dwindled with water levels in the habitat.

Biosphere 2 was built as a sealed habitat for humans, but the first two "missions" failed and it has evolved into a laboratory owned by the University of Arizona.

ORACLE, AZ — Four dozen Sonoyta pupfish are now swimming beneath the towering glass pyramids of the University of Arizona’s Biosphere 2 after a multi-year effort to conserve the critically endangered species.

The rare desert fish were introduced into a newly constructed desert stream habitat at the research facility on Oct. 24, welcomed by a cheering crowd of universit