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Tequila Splitfin: Facing Extinction for 20 Years

The Tequila splitfin (Zoogoneticus tequila), is a small freshwater fish measuring up to 8cm long – with females being slightly larger than males. They are endemic to the Teuchitlan Springs in the upper Ameca river basin in Mexico, where they inhabit small lakes, tributaries and freshwater springs.
The species is named after the Tequila volcano, which overlooks the small lake where they were discovered for the very first time in 1955. However, it was not until 1998 that they were officially classified as their own species. Their original habitat was a small lake with a diameter of just 8 metres and a depth of 1.3 metres.

A series of unsuccessful searches caused them to be reported as “extinct in the wild” in 1998. Just three years later, in 2001, a small population containing just a handful of adults was discovered. Again, this was in a small lake that measured between 3 and 4 metres in diameter. Unfortunately, this population was reported as extinct in 2013.
In 2015 a reintroduction programme began, driven by captive breeding projects around the world. The IUCN (International Union for Conservation of Nature) estimated this population to have around 80 adults in 2018, with numbers growing at a steady rate. This new population inhabits an oxygen rich freshwater spring which is 4 metres in diameter and an average depth of just twenty centimetres.


The survival of the Tequila splitfin now faces a multitude of threats in the wild. These include:

  • Habitat degradation
  • Introduction of exotic fish species
  • Introduction of exotic diseases
  • Agriculture and aquaculture
  • Human disturbances
  • Changes in water management
  • Pollution

Thankfully, there are already a number of conservation measures in place out in Mexico. These include:

  • Research and monitoring
  • Land and water protection
  • Species management via captive breeding projects
  • Education

The Future

Nobody can guarantee the survival of this species, the odds are certainly stacked against them. However here at Blue Planet Aquarium, we believe that every species is entitled to a fair shot at survival, especially when it’s decline is largely caused by human activity.
Here at Blue Planet Aquarium, we now have a healthy group of Tequila splitfins. Thanks to Bolton Museum Aquarium, we were able to become part of a nationwide captive breeding programme. This will allow Blue Planet Aquarium to contribute new offspring to other collections that will work towards ensuring the future of this characterful species. Hopefully in time, the waters of the Ameca river will teem with Tequila splitfins once again.
Author: Dan Goodyer, Aquarist at Blue Planet Aquarium 


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