The distribution patterns and diversity of fish communities and their spatial variation as a function of environmental parameters between the head and the mouth were studied in the Río Plátano, Honduras. In October 2011 the recollection of environmental data and occurrence of fish in 25 stations was executed, using electro-fishing, hook, cast nets and beach seine. A total of 1297 specimens was recollected, represented in 29 species, 27 genus, 17 families and 6 orders, no exotic species were detected. The number of species reported for the river increased from 30 to 44. The families that contributed more species to the study were Cichlidae and Poeciliidae. Alfaro huberi was the species with the highest abundance and distribution. The mouth was the station that had the highest abundance and species richness. Both the NMDS as the ACC show a clear longitudinal gradient, the height above sea level and percentage of environmental habitat were the factors that best describe the variation of the distribution and abundance of fish in the river, allowing differentiate one clear longitudinal zonation in the river: upstream, middle and lower zone.