Mexican fish extinct in the wild has been successfully reintroduced


Its success is now closely linked to the identity of the community and praised internationally.

It started over two decades ago in Teuchitlán, a town near the Tequila volcano. Half a dozen students, including Omar Domínguez, began to worry about the small fish that held in the palm of one hand and had only ever been seen in the Teuchitlán River. It had disappeared from local waters, apparently due to pollution, human activities and the introduction of non-native species.

Domínguez, now a 47-year-old researcher at the University of Michoacán, says that at the time, only the elderly remembered the fish called “gallito” or “little rooster” because of its orange tail.

In 1998, environmentalists from Chester Zoo in England and other European institutions arrived to help set up a Mexican fish conservation laboratory. They brought several pairs of splitfin tequila fish from collectors’ aquariums, Domínguez said.

The fish began to reproduce in aquariums and a few years later, Domínguez and his colleagues took the gamble of reintroducing them into the Teuchitlán River. “They told us it was impossible, (that) when we gave them back they were going to die.”

So they looked for options. They built an artificial pond for a semi-captive training course and in 2012 they put 40 pairs there.

Two years later there were some 10,000 fish. The result secured funding, not only for the Chester Zoo but also for a dozen organizations from Europe, the United States and the United Arab Emirates, to move the experience to the river.

There they studied parasites, microorganisms in the water, interaction with predators, competition with other fish, and then introduced the fish to floating cages.

The aim was to restore the fragile balance. For this part, the key was not so much the scientists as the local residents.

“When I started the environmental education program I thought they were going to turn a deaf ear to us… and at first it happened,” said Domínguez.

But environmentalists have succeeded with patience and years of puppet shows, games, and explanations of the ecological and health value of “tequila zoogoneticus” – the fish help control the mosquitoes that spread dengue fever.

Some locals have invented a nickname for the little fish: “Zoogy”. They made cartoons and trained the “Keepers of the River”, a group made up mostly of children. They collect trash, clean the river and remove invasive plants.

Domínguez said it is difficult to say if the water quality is better because there is no past data to compare, but the whole ecosystem has improved. The river is cleaner, there are fewer non-native species, and cattle are no longer allowed to drink in some areas.

The fish quickly multiplied inside their floating cages. Then they were tagged so that they could be tracked and released. It was the end of 2017 and in six months the population has increased by 55%. By the last month, the fish had spread to another part of the river.

Reintroducing extinct species into the wild is complex and time consuming. Examples of success are Przewalski’s horse and Arabian oryx. The Chester Zoo said on December 29 that splitfin tequila had joined this small group.

“The project was cited as an International Union for the Conservation of Nature (IUCN) case study for successful global reintroductions – with recent scientific studies confirming that fish are already thriving and reproducing in the river,” the zoo said in a statement.

“This is an important moment in the battle for species conservation,” said Gerardo García, conservator of lower vertebrates and invertebrates at the zoo.

The IUCN Red List of Threatened Species lists splitfin tequila as endangered. Mexico’s freshwater ecosystems are under pressure from pollution, overuse of water resources and other factors. More than a third of the 536 assessed freshwater fish species in the country are threatened with extinction, according to a 2020 report led by IUCN and ABQ BioPark in the United States.

However, in Mexico, Domínguez and his team are already starting to work on another fish considered to be extinct in the wild: the “skiffia francesae”. The Golden Skiffia could one day join “Zoogy” in the Teuchitlán river.


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