Nesiarchus nasutus
Nesiarchus nasutus, the black gemfish or violet snake mackerel, is a species of snake mackerel 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 migrations 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.