N. helfrichi mainly feed on zooplanktons, amphipods, copepods, small crustaceans and shrimp larvae.

[3][8][9] The species is shy and hides in small caves when threatened.

[9] Due to their bright colour they are very popular as a marine aquarium fish.

They are also more delicate and rare form than other more common firefish species (as evidenced by their price) and should be kept by marine-aquarists of intermediate expertise or higher.

The specific name honours Philip Helfrich, an Emeritus Director and Researcher, Hawaii Institute of Marine Biology (University of Hawaii), and the director of the Eniwetok Marine Biological Laboratory, who collected some of the first specimens of this species.