The Chapultepec splitfin (Girardinichthys viviparus), known locally as mexcalpique, is a critically endangered species of fish in the family Goodeidae.

Most native populations disappeared as they were at or near Mexico City, with the waters either being reclaimed, drained, heavily polluted or infested with introduced species.

Today the Chapultepec splitfin is only known to survive in three lakes (Viejo, Menor and Mayor) in the Chapultepec park of Mexico City, Lake Xochimilco, Lake Zumpango, Laguna de Tecocomulco northeast of the City where perhaps introduced, and parts of the Pánuco River basin.

[4] This species was originally described as Cyprinus viviparus in 1837 by Miguel Bustamante y Septién with the type locality given as "Mexico".

[5] In 1860 Pieter Bleeker raised the genus Girardinichthys with a new species Girardinichthys viviparus as its type species, this subsequently proved to be a taxonomy of Cyprinus viviparus.