A cardinalfish so small and so nearly transparent that the most visible part of it is the eye: about 3.5 cm (1.4 in), with the silvery gut showing through the body wall. It lives deep inside caves and under coral slabs, frequently hovering upside down against the ceiling.
Transparency works only in the dark, which is why this fish never leaves shade. A torch aimed into a cave picks up a cluster of eyes with almost nothing attached to them, which is the usual way anyone notices the species at all. It feeds on plankton drawn into the cave by surge, and the males brood eggs in the mouth like their larger relatives. Records are few, mostly because looking for a transparent 3 cm fish inside a cave requires deliberately going in and waiting for your eyes to adjust.
- tiny and almost transparent, with silvery internal organs showing
- hovers upside down under cave ceilings
- large dark eye, the most visible part of the fish
- length up to 3.5 cm
