The fossil record of Mexican freshwater fishes, although scarce, has increased in recent years. These fossils are known in 39 localities, 4 of which are Cretaceous and carry remains of cf. †Melvius sp., Amiidae, Lepisosteidae and †Ceratodus sp., groups no longer recorded as fossil material in subsequent periods. The remaining localities belong to the Cenozoic Era (Oligocene to Pleistocene) and contain modern faunas; most of them are located in the Mexican Volcanic Belt and most are from Pleistocene deposits. The diversity of fossil fish includes 12 families and at least 26 genera, and 39 species. Only some of the latter are known as fossils. The position of the Cenozoic localities in relation to existing drainage and fish communities suggests events of change in the hydrology for some recent basins. In order to broaden the knowledge on this group of fishes, it is required to perform active prospective work in less explored areas such as Northern endorheic drainages and Southern tropical basins of Mexico, in addition to applying finer recovery and study techniques, as well as incorporating new procedures for, among others, molecular and isotopic analyses. | El registro fósil de los peces de agua dulce en México, si bien es escaso, se ha visto incrementado durante los últimos años. Estos fósiles se conocen en 39 localidades, de las cuales 4, ubicadas en el norte del país, son cretácicas y cuentan con restos de cf. †Melvius sp., Amiidae, Lepisosteidae y †Ceratodus sp., grupos que no vuelven a registrarse como fósiles en periodos posteriores. Las demás localidades son cenozoicas (Oligoceno a Pleistoceno) y poseen faunas modernas; se ubican principalmente en la Faja Volcánica Transmexicana y la mayoría son pleistocénicas. La diversidad de peces fósiles incluye 12 familias y por lo menos 26 géneros y 39 especies, y de estas últimas, algunas únicamente son conocidas como fósiles. La ubicación de las localidades cenozoicas con relación a los drenajes e ictiofauna actuales sugiere eventos de cambios en la hidrología de algunas cuencas recientes. Para ampliar el conocimiento sobre este grupo de peces se requiere realizar trabajo prospectivo activo en las zonas menos exploradas, como los bolsones del norte y las cuencas tropicales del sur de México, aplicar técnicas de recuperación y de estudio más finas, así como incorporar las nuevas técnicas para análisis moleculares e isotópicos, entre otros.

The fossil record of Mexican freshwater fishes, although scarce, has increased in recent years. These fossils are known in 39 localities, 4 of which are Cretaceous and carry remains of cf. †Melvius sp., Amiidae, Lepisosteidae and †Ceratodus sp., groups no longer recorded as fossil material in subsequent periods. The remaining localities belong to the Cenozoic Era (Oligocene to Pleistocene) and contain modern faunas; most of them are located in the Mexican Volcanic Belt and most are from Pleistocene deposits. The diversity of fossil fish includes 12 families and at least 26 genera, and 39 species. Only some of the latter are known as fossils. The position of the Cenozoic localities in relation to existing drainage and fish communities suggests events of change in the hydrology for some recent basins. In order to broaden the knowledge on this group of fishes, it is required to perform active prospective work in less explored areas such as Northern endorheic drainages and Southern tropical basins of Mexico, in addition to applying finer recovery and study techniques, as well as incorporating new procedures for, among others, molecular and isotopic analyses.