By MARÍA VERZA
MEXICO CITY (AP) — There once was a small fish called “tequila splitfin” or “zoogoneticus tequila” that swam in a river in western Mexico, but disappeared toward the end of the 20th century. Scientists and local residents, however, have achieved the return of a species extinct in nature _ but conserved in captivity _ to its native habitat. Its success is now not only intertwined with the community’s identity, but it’s also touted internationally as an example of best practices. Still, Mexico’s freshwater ecosystems are under severe pressure from pollution, over-extraction of water resources and other factors. Many freshwater fish species in the country are threatened with extinction.