Here are two
common gobies which look much alike and occur in similar habitat.
Both are pale gray or whitish with markings that help them blend
into the sand. Both have a dark line extending through the eye and
down the side of the head. Both have a small yellow spot on the
"shoulder" above the pectoral fin. And both live singly
or in groups on sand and rubble at the bases of coral heads, boulders,
or walls, retreating into crevices when alarmed.
Gnatholepis anjerensis (Bleeker, 1850)
This goby has scattered dark and white specks on the body and a
row of smudgy dark spots along the lower side.There is a tiny, scarcely-visible
bright yellow spot above the pectoral fin base. The dark lines
through the eye do not meet at the top of the head. It tends
to live at depths above 40 ft. When sensing a predator, these gobies
bob rhythmically up and down, probably to warn other gobies of danger
and also to inform the predator that it is detected. The species
name is from Anjer, Indonesia, where the fish was first collected.
To about 3 in. Indo-Pacific. Photo: Magic Island boat channel, O`ahu.
Gnatholepis cauerensis (Bleeker, 1853)
This goby has fine dark lines along the side instead of rows
of dark spots, and the eye bars meet at the top of the head.
The yellow "shoulder spot" is vertically elongated and
slightly larger than that of the Eye-Bar Goby. This species usually
occurs at 40 ft. or more, slightly deeper than the Eyebar. The name
is from Cauer, the locality in Java where Bleeker obtained his specimens.
To about 3 in. Indo-Pacific. Photo: Mäkua, O`ahu. 50 ft.