The two-decade efforts to recover an extinct Mexican fish have finally paid off. The findings detailing this achievement were announced in a report posted by The Associated Press on January 2.
The small fish, called “tequila splitfin” or “gallito” or “little rooster” because of its orange tail, swam in a river in western Mexico but disappeared in the 1990s, apparently due to pollution, human activities and the introduction of non-native species.
In 1998, conservationists from the Chester Zoo in England and other European institutions arrived to help set up a laboratory for conserving Mexican fish. They brought several pairs of tequila splitfin fish from the aquariums of collectors.
The fish began reproducing in aquariums and within a few years, the researchers gambled on reintroducing them to the Teuchitlán river. This goal was achieved recently, although many believed they were going to die once returned to the river.
“When the fish began reproducing, the researchers 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. The result guaranteed funding, not only from the Chester Zoo but also a dozen organizations from Europe, the United States and the United Arab Emirates, to move the experiment to the river,” said Omar Domínguez, researcher at the University of Michoacán and co-author of the study.
There they studied parasites, microorganisms in the water, the interaction with predators, competition with other fish, and then introduced the fish in floating cages.
The establishment of these cages in 2017 was aimed at testing the quality of water, because there is no previous data to compare. But the researchers found that the fish rapidly multiplied inside their floating cages, and their population increased 55 percent in six months, until they became among the remarkable fish in the river by the end of 2021.
The reintroduction into nature of species that were extinct in the wild is complex and time-consuming. Przewalski’s horse and the Arabian oryx are among successful examples. The Chester Zoo said December 29 that the tequila splitfin had joined that small group.
