The Paraíba do Sul basin is home to just above 100 native fish species with most in the families Loricariidae, Characidae and Trichomycteridae.[5] About 40% of the fish species in the river basin are endemic (the genus Oligobrycon is entirely restricted to the basin)[5] and new species have been discovered in recent years, including the small catfish Pareiorhina hyptiorhachis that only was scientifically described in 2013.[6]