Resumen:
The primary objective was to document the diversity of fishes in Reserva de la Biosfera Barranca de Metztitlan, Hidalgo, Mexico. Samples were collected from 35 localities using electrofishing, nets, and angling, and from local fishermen. A total of 7,290 specimens was collected, representing 16 species (including 4 introduced and 4 translocated). This study adds seven species to the regional fish fauna, five of which are exotic.