Diaphus bertelseni, or Bertelsen's lanternfish, is a species of oceanodromous lanternfish, first described in 1966 by Basil Nafpaktitis.

[2][3] The species epithet, bertelseni, honours the Danish ichthyologist, Erik Bertelsen.

[3] Diaphus bertelseni lives in the Eastern Atlantic, Western Atlantic, Southwest Pacific, and Eastern Pacific at depths up to 300 meters.

[4] Diaphus bertelseni grows to a length of 9.1 cm, and can have up to 15 dorsal fins, 15 anal fins, 8 pelvic fins, 18 gill rakers, and 35 lateral lines.

[2] Their coloring is dark with paler photophores.