Most deep-sea fish have visual pigments that are most sensitive to wavelengths around 460-490 nm, the intensity maxima of both conventional blue bioluminescence and dim residual sunlight. The predatory deep-sea dragon fish Malacosteus niger, the closely related Aristostomias sp. and Pachystomias microdon can, in addition to blue bioluminescence, also emit far-red light from suborbital photophores, which is invisible to other deep-sea animals. Whereas Aristostomias sp. enhances its long-wavelength sensitivity using visual pigments that are unusually red sensitive, we now report that M. niger attains the same result using a derivative of chlorophyll as a photosensitizer.