Sladenia shaefersi was first formally described in 1976 by the American ichthyologists John H. Caruso and Harvey R. Bullis with its type locality given as Point Barú on the Caribbean coast of Colombia.

[2] The genus Sladenia is one of 4 extant genera in the family Lophiidae which the 5th edition of Fishes of the World classifies in the monotypic suborder Lophioidei within the order Lophiiformes.

The specific name shaefersi honors Edward A. Schaefers, the former chief of the Exploratory Fishing and Gear Research Branch of the now renamed Bureau of Commercial Fisheries.

[4] Sladenia shaefersi has a rounded, rather than depressed head with a obviously convex nape, the rear of the body and caudal peduncle are compressed rather than flattened.

[1] It is a bathydemersal species found at depths between 900 and 1,200 m (3,000 and 3,900 ft),[6] on coral rubble on the continental slope and on seamounts.