Photostylus is a monospecific genus of deepwater maineray-finned fish belonging to the familyAlepocephalidae, the slickheads. The only species in the genus is Photostylus pycnopterus, the starry smooth-head, a species found in all oceans at depths of from 1,000 metres (3,300ft) to 2,000 metres (6,600ft). This species grows to a length of 11 centimetres (4.3in)SL.