Phosichthyidae

Lightfishes are small stomiiform fishes in the family Phosichthyidae^[1][2]

Lightfishes Temporal range: Lutetian–present PreꞒ Ꞓ O S D C P T J K Pg N
Ichthyococcus ovatus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Stomiiformes
Suborder:	Phosichthyoidei
Family:	Phosichthyidae Weitzman, 1974
Genera
Ichthyococcus Phosichthys Pollichthys Polymetme Vinciguerria Woodsia Yarrella
Synonyms
Photichthyidae

The earliest fossils of lightfishes are of the genus †Sytchevskia Prokofiev, 2002, known from Middle Eocene-aged Tethyan marine strata in Georgia.^[3][4]

They are very small fishes found in oceans throughout the world: most species grow no longer than 10 cm, while those in the genus Vinciguerria only reach 4 cm or so.

They make up for their small size with abundant numbers: Vinciguerria is thought — with the possible exception of Cyclothone — to be the most abundant genus of vertebrates. Deep-sea trawls of the Humboldt Current in the southeast Pacific have found that lightfishes make up 85% by mass of mesopelagic fishes, with Vinciguerria lucetia by far the most numerous species.^[5]

They are bioluminescent fishes, possessing rows of photophores along their sides, with which they hunt planktonic invertebrates, especially krill, copepods, and planktonic amphipods.^[6]