Broom Filefish

You can sex this fish by what it carries on the side of its tail. Males grow five or six long, stiff, backward-pointing quills there. Females grow a dense pad of bristles in the same place that looks like the head of a worn toothbrush. The Latin name records it: scopas means broom.

Both structures are made of the same stuff as the rest of the skin. Filefishes are covered in minute scale spinules, rough enough under a fingertip that the family is named for a woodworking tool, and on the tail base of this species that roughness is drawn out into either spikes or a scrub brush. It is the only fish in its genus.

Look for a deep, flattened, almost disc-shaped body in dark brown, crossed by eight to twelve narrow darker bars, with pale to yellow soft dorsal and anal fins and a dark tail. The mouth is tiny and sits at the front of a short snout. One long spine stands over the eye and folds flat into a groove on the back. It reaches 20 cm.

That spine is the family's real defense, and it is the same device the triggerfishes use. A second, much smaller spine drops in behind it and jams it upright. A broom filefish that has backed into a hole with the spine locked and the flap of skin under its belly spread is wedged in place: pull on the tail and the fish tears before it moves.

It feeds on coral polyps, alone or in pairs, over clear coastal and outer reefs where coral heads sit among rubble and gutters, from just under the surface to about 18 m. It is shy and it does not wait around, so most 🌊 Red Sea divers meet it as a dark shape sliding behind a coral head. Regular here without being numerous, and noticed far more often than it is photographed.

Forty-two of them were aged from their ear stones in the 🇸🇧 Solomon Islands and the oldest was twelve years, which is a long life for a fish that stops growing at 20 cm.