Fishes are a paraphyletic group composed by craniates except for the four-limbed clade Tetrapoda. This group was the only vertebrate representative until the Devonian but now comprises almost half of the vertebrate species, dominating nearly all aquatic environments. The fossil record is the key to understand the ancient paleobiodiversity and the patterns that lead the modern fish fauna, and paleontological collections play a fundamental role in providing accommodation, maintenance, and access to the specimens and their respective metadata. Here we present a systematic checklist of fossil fishes housed in the type collection of the Colección Nacional de Paleontología which is located at the Instituto de Geología of Universidad Nacional Autónoma de México. Currently housed in the type collection are 14 chondrichthyan specimens, belonging to two superorders, five orders, seven families, 10 genera, and five nominal species, and 361 osteichthyan specimens, belonging to eight orders, nine families, nine genera, and 26 nominal species. These fossils come from 32 localities and 15 geological units, which range temporally from the Jurassic to the Pleistocene. The paleoichthyofauna housed in the type collection of the Colección Nacional de Paleontología is remarkable for its singularity and reveals new insights about the origin and diversification of many groups of fishes. The recovery and curation of this fossil material indicates that knowledge of Mexican fossil fish diversity and its role in understanding lower vertebrate evolution are just emerging and reaffirms the importance of the biological and paleontological collections to the future biodiversity research.
