Once extinct in the wild, the Tequila fish is the first Mexican fish to ever come back from so close to the brink.

A project to save this diminutive creature began all the way back in 1998 and has finally culminated in their successful reintroduction back into the rivers of Mexico. Conservationists say it’s been a tough slog to save the green, 7cm long fish that most people have never heard of, but they believe it can be a rallying cry to help protect the country’s waterways.
“It’s a project which has now set an important precedent for the future conservation of the many fish species in the country that are threatened or even extinct in the wild, but which rarely take our attention,” Professor Omar Dominguez, from the Michoacana University of Mexico, told the BBC.
Back in 1998, Chester Zoo in England gave five female and five male Tequila fish to Michoacana University, who carefully nurtured them into larger and larger numbers. Finally to number 10,000.
The river population is now growing steadily, and the IUCN has re-evaluated the species from Extinct in the Wild to Endangered status. “This just goes to show that animals can re-adapt to the wild when reintroduced at the right time and in the right environments,” says conservationist Gerardo Garcia.
If you're wondering why they are called Tequila fish, it derives from the Tequila Volcano, which looms near their riverine habitat north west of Guadalajara.