Atherinomorus insularum

Atherinomorus insularum also called Hawaiian silverside or 'iao in Hawaiian is a species of fish in the family Atherinidae endemic to Hawaii.

Description and biology
The Hawaiian silverside has two dorsal fins and a prominent lateral stripe, which sets them apart from other baitfish. They can grow up to three and a half inches. They are greenish gray on the back and have a silvery stripe topped by a blue-green line running the length of the body. They disperse to feed on plankton at the surface at night.

Distribution and habitat
Atherinomorus insularum are endemic to Hawaii. They are a common schooling fish often found near the surface in tidepools and coastal waters.

Human use and cultural significance
In ancient Hawaii, these fish were sometimes used to rub the face of a human sacrificial victim to make it shine like the eyes of a maneater shark.