Branchinecta brushi is a new species of fairy shrimp described from a pool within the volcanic crater of Cerro Paniri, northern Chile. Its occurrence represents a new altitude record for anostracans (5930 m), and it shares the title for highest altitude occurrence across all of Crustacea with a cladoceran from the same pool, Boeckella palustris. Branchinecta brushi is similar to another Chilean anostracan, B. valchetana. However, B. brushi differs from B. valchetana in the detailed morphology of the male second antennae and gonopods. Male specimens of B. brushi possesses a bulbous, distally spinose medial apophysis on the proximal article of its second antenna as well as short, stout, inwardly curved gonopods. Both sexes are distinguished by very short cercopods. Bringing phylogenetic order to the monogeneric family Branchinectidae will require increased levels of morphological documentation and a better understanding of intra-specific variation. Most crustaceans are not well suited to life at high altitudes; those that thrive at high elevations offer insights not only to their biological tolerances, but also to their various modes of dispersal.