Herwigia is a monospecific genus of deepwater maine ray-finned fish belonging to the family Alepocephalidae, the slickheads. The only species in the genus is Herwigia kreffti, or Krefft's smooth-head, a species found at depths of 1,000 to 3,200 metres (3,300 to 10,500 ft) in the oceans. This species grows to a length of 40 centimetres (16 in) SL.