Glassfish (Sweepers)

Glassfish (or pygmy sweepers) form impossibly dense schools that fill caves and overhangs — translucent body silver-pink-orange, eye prominent, and tens of thousands moving in coordinated waves that look like flowing curtains.

Light passing through their bodies creates ethereal photo opportunities — divers swimming through a cave full of glassfish can capture an almost otherworldly scene. Caves in the Red Sea (Ras Mohammed, Daedalus), Maldives overhangs, Andaman walls all hold them.

Bumphead parrotfish and giant trevally famously hunt these schools — sit at a known glassfish cave at dawn and the predator strikes are spectacular.