''Nesiarchus nasutus'', the Black gemfish, is a species of

snake mackerel The snake mackerel (''Gempylus serpens'') is the sole species of fish in the monotypic genus ''Gempylus'', belonging to the family Gempylidae (which is also referred to generally as "snake mackerels"). It is found worldwide in tropical and sub ...

found in tropical and subtropical waters in most parts of the world, though not in east Pacific and north Indian waters. It occurs at depths of from though they make

diel vertical migration Diel vertical migration (DVM), also known as diurnal vertical migration, is a pattern of movement used by some organisms, such as copepods, living in the ocean and in lakes. The word ''diel'' comes from the Latin ''dies'' day, and means a 24-h ...

s from benthopelagic to mesopelagic depths at night. This species can reach a length of SL though most do not exceed SL. It is of minor importance to local commercial fisheries. This species is currently the only known member of its genus, ''Nesiarchus''. That genus is thus considered monotypic.

References

Mackerels Gempylidae Fish described in 1862 Monotypic fish genera Taxa named by James Yate Johnson {{Scombroidei-stub