Mephisto fraserbrunneri Was first formally described in 1966 by the American ichthyologist James C. Tyler with its type locality given as the Bay of Bengal at 10°39'N, 97°06'E from a depth of 159 fathoms (954 ft; 291 m).

[3] The 5th edition of Fishes of the World classifies the family Triacanthodidae in the suborder Triacanthoidei in the order Tetraodontiformes.

The specific name honours the British ichthyologist Alec Fraser-Brunner, who when Tyler described this species was director of the Van Kleef Aquarium in Singapore, for his work on fishes in the order Plectognathi.

The gill slit is long, reaching down as far as just under the lower edge of the base of the pectoral fin.

The diet was dominated by formaniferans, both benthic and pelagic species, as well as pteropods, tusk shells, echinoderm parts and crustaceans.