Inside the International Effort to Save One Tiny Mexican Fish

This story was originally published on Atlas Obscura.

There is nothing remarkable about Mexico's split fin fish. The fish are only 2 inches long. They are not particularly fast. They don't change colors or exhibit strange behaviors. They are not memorable in many ways. When the fish, endemic to only a single spring-fed river in the Mexican state of Jalisco, went extinct in 2003 there was no international outcry or even an article in a local newspaper to bid them farewell.

The scientists at Michoac University knew that the fish, known as the tequila fish, played an important role in the river. In the 1990s, an international team of scientists joined forces to save the fish. After it went extinct in 2003 the team would attempt something that had never been done before in Mexico. Almost two decades have passed since the population of tequila fish, some 2,000 strong, once again called the Teuchitl River home, swimming in the crystal waters in the shadow of the tree-covered hillside.

The project began in 1998 when English aquarist Ivan Dibble arrived at Michoac University with some very precious cargo. The extinction of the tequila fish was likely caused by pollution and other invaders, according to scientists at the zoo. Scientists could provide a controlled environment for the fish in captivity.

The biologists at Michoac cared for the fish for 15 years. This was the first time scientists tried to do a reintroduction program in Mexico. If the project failed, all the people would say it was impossible to re-fish.

A colony of 10 fish grew. 40 pairs of fish were transferred to an artificial pond at the university. They had to prove that the fish could survive in a semi-natural environment. In the pond, the fish had to compete for food, contend with parasites, and avoid predator like turtles, birds, and snakes, just as they would in the wild. The school grew to an estimated 10,000 after four years. The money needed to return the fish to the wild was raised thanks to that success.

The only way to make that happen was to get the local community involved. The fish could die out again if the residents don't clean and protect the river. The professor of environmental education at Michoac was called in. He got to work with volunteers like Martha and Pilar who founded the community initiative. As Valencia and local volunteers painted murals of the fish around town, local children chose a nickname for it. In the 20th century, locals called the fish gallito because of the strip of bright orange that decorates the tails. The fish was referred to as a burrito by others, though Perla Espinoza is at a loss to explain why.