Eschmeyer nexus was first formally described in 1983 by the American ichthyologists Stuart G. Poss and Victor G. Springer with the type locality given as Fiji.

[5] A recent study placed the genus Eschmeyer into an expanded stonefish clade, the Synanceiidae, because all of these fish have a lachrymal sabre that can project a switch-blade-like mechanism out from underneath their eye.

[6][7] The name of both the genus and family honours William N. Eschmeyer, an American ichthyologist at the California Academy of Sciences, or his work on the Scorpaenid fishes.

The specific name nexus, is derived from nectere, Latin for 'tie' or 'connect', a reference to the suite of features suggesting this taxon has a close relationship with a number of groups within the Scorpaenoidei.

Mandritsa suggested the English common name of cofish in recognition of Eschmeyer’s participation in the Catalog of Fishes.