HAWAIIAN SILVERSIDE · `iao · Atherinomorus insularum (Jordan & Evermann, 1905)
(Note: The photos of this fish in the 1st and 2nd printings of Hawaii's Fishes and the Ultimate Guide to Hawaiian Reef Fishes incorrectly show Delicate Roundherrings and vice versa)
     These small fish live in large tide pools, brackish pools, on shallow protected reef flats, and off rocky shorelines, often in large numbers. Greenish gray on the back, they have a silvery stripe topped by a blue-green line running the length of the body. At night they disperse to feed on plankton at the surface. In ancient Hawai`i these fish were said to be phosphorescent; the face of a human sacrificial victim was sometimes rubbed with them “so that it shone like the eyes of the maneater shark of the deep.” To about 3 1/2 in., but usually much smaller. Endemic (with a sister species, A. lacunosus, elsewhere in the Indo-Pacific). Photo: Leleiwi Beach Park, Hawai`i.

Note: On shallow reef flats the Hawaiian Silverside is easily confused with the similar Delicate Roundherring (Spratelloides delicatulus), which shares that habitat. Silversides have two dorsal fins, the first arising at the center of the back and the second almost directly over the anal fin. The roundherrings have only one dorsal fin.