MEXICO CITY — There once was a small fish called “ tequila splitfin ” or “ zoogoneticus tequila ” that swam in a river in western Mexico, but disappeared in the 1990s.... “ They told us it was impossible,( that) when we returned them they were going to die.” Story continues below advertisement So they looked for options.... They built an artificial pond for a semi-captivity stage and in 2012 they put 40 pairs there. Two years later, there were some 10, 000 fish....