It lives on the ceiling.
Cave cardinalfish hang under the roofs of caves and deep overhangs, frequently inverted, in permanent shade a few meters from bright sunlight. That is a real habitat with its own rules: no algae, because there is no light for it; no current to speak of; a constant rain of organic material from the reef outside; and, crucially, very few predators, because a cave roof is a dead end and hunting fish avoid dead ends.
What it selects for is what you see in the animal. Enormous eyes, because the light budget is tiny. Pale, almost colorless bodies, because in permanent dimness there is nothing to hide from and nothing to signal to. And a willingness to orient any way at all, since up and down stop meaning much when you spend your life against a roof.
The same cave-roof community turns up wherever there are caves on this coast: soldierfish, bigeyes, glassfish and this small pale cardinalfish, all with the same oversized eyes and the same reluctance to come out.
It lives in this sea and nowhere else, between about six and twenty meters.
The genus. Zapogon Fraser 1972 - zá- (intensive particle). ETYFish
The species. Zapogon isus (Randall & Böhlke 1981) - from ísos (ἴσος). ETYFish
- pale pinkish body with a dark bar through the eye
- hangs under cave roofs and deep in overhangs, often upside down
- very large eye for the head
- up to 5.6 cm
