Look under a ledge or into a cave mouth in daylight and you may find a cloud of these fish hanging almost motionless, packed tight, all facing the same way. They are waiting for dark. At night the shoal breaks up and the fish spread out to take zooplankton.
The males brood. After the female lays, the male takes the whole clutch into his mouth and holds it there for about a week, rolling it to keep water moving over the eggs, and he cannot feed while he does it. That cost is high enough that hungry brooding cardinalfish are known to swallow part of their own clutch: a bad outcome for those eggs, but it keeps the male alive to breed again.
Up close the body is translucent pink crossed by dozens of fine orange lines, with a dark spot at the base of the tail. In a shoal the lines blur together and the whole group reads as a pale orange haze, which is rather the point.
The genus. Taeniamia Fraser 2013 - taenia (band or ribbon). ETYFish
- translucent pink body crossed by dozens of fine orange lines
- dark spot at the base of the tail
- large eye with an orange bar through it
- hangs in dense, near-motionless shoals by day
- up to 10 cm
