Tequila Fish: Scientists Reintroduce This Mexican Fish Once Considered Extinct

Scientists have successfully reintroduced a fish species that was considered lost in the wild for over 15 years. The species is thriving yet again.

The Zoogoneticus tequila, also known as the tequila fish or tequila splitfin, is a small fish that once swam in the waters in the Teuchitlán river in western Mexico, AP News reported. It is an endemic species, which means it can only be found in its specific geographic location.

The introduction of exotic invasive species, as well as water pollution, had caused the species to vanish. It "disappeared from the wild completely" in 2003, Chester Zoo noted in a news release. By 2013, the species was declared to be extinct in the wild.

However, that was not the end of the tequila fish's story. Scientists at the Michoacana University of Mexico received five pairs of the fish from Chester Zoo in 1998. Experts from the zoo, as well as from other institutions, helped to set up a laboratory for the species' conservation and future reintroduction to their habitat.

"They told us it was impossible, (that) when we returned them they were going to die," said Omar Dominguez, a researcher at the Michoacana University of Mexico.

The species' population continued to grow in the laboratory for 15 years. To prepare for their reintroduction, scientists released 40 females and 40 males into large artificial ponds in 2012, AP News noted. The population grew to 10,000 individual fish in just a few years. With funding from organizations from various countries, the researchers moved the experiment to the river.

Thankfully, the water in the river had become cleaner, and there were fewer non-native species. The tequila fish multiplied "rapidly" in their floating cages and were set free in 2017. Their population increased by 55% in just six months, AP News reported.

The tequila fish is now "thriving" with the help of the local people who were educated on the value of the fish. They had already expanded to another part of the river.

"It is a real privilege to have helped save this charismatic little fish and it just goes to show that with the skill and expertise of conservationists, and with local communities fully invested in a reintroduction project, species can make a comeback from environments where they were once lost," Gerardo Garcia, the Curator of Lower Vertebrates and Invertebrates at Chester Zoo, said in the news release.

"Following years of hard work by our partners at the Michoacana University of Mexico, the wild population is, thankfully, now thriving–they're breeding naturally at a tremendous rate. It very much goes to show that animals can re-adapt to the wild when reintroduced at the right time and in the right environments. Our mission is to prevent extinction and that's exactly what we've done here," Garcia added.

This is said to be the first time that an extinct fish species is successfully reintroduced in Mexico, Dominguez said a statement from the zoo. The case of the tequila fish is now considered as an "International Union for the Conservation of Nature (IUCN) case study for successful global reintroductions," serving as a "blueprint" for future such efforts to save other endangered fish.