The Potosi Pupfish ("Perrito de Potosi") was endemic to only one large, clear spring-fed pool near El Potosi in northeast Mexico.
Sadly it and the Catarina Pupfish, Megupsilon aporus, and a crayfish from the same pool are all now extinct in the wild
following human drainage of the pool for irrigation from 1984 to the 1990s.
Breeding male.
Breeding female.
Non-breeding.
The breeding male, above left, has beautiful milky white irridescent scales and a thick black border to the tail fin.
They grow to 5-6cm long.
The Catarina Pupfish became totally extinct in 2015 but a few Potosi Pupfish survive in captivity in a
North American and a British aquarium.