Faintstripe Filefish

Two sets of records describe this fish and they do not sound like the same animal. The scientific literature has it from trawl grounds, on mud and sand between 28 and 79 m, coming up as bycatch. The regional dive guide photographs it in a protected bay at Dahab, over sand and seagrass, in water shallow enough to snorkel. Both are right. It is a soft-bottom fish, and soft bottom exists at both depths.

Rueppell described it from 🌊 Red Sea material in 1829, so this is one of the sea's long-known fishes, and it still goes largely unseen, because the places it likes are the places most dives skip: sheltered bays, sand flats, seagrass. There is no structure there to hold divers.

At around 15 cm it is the largest of the small filefishes on this coast. The body is deep and strongly compressed, almost leaf-shaped from the side and nearly edge-on invisible from the front. The faint stripes that give it its name run along the flank and are often so weak they vanish in a photograph. The mouth is small and set at the front, and the first dorsal spine stands over the eye and folds into a groove on the back.

That spine is the family's insurance. It locks upright when a small second spine drops in behind it, exactly as in the triggerfishes, and a filefish jammed into cover with the spine up and its belly flap spread does not come back out. The skin is the other half of the family name: covered in minute spinules and rough as a file.

Over seagrass it hangs among the blades, drifting rather than swimming, and its pattern settles toward whatever it is standing in. Feeding is small work, invertebrates and plant material taken off the bottom and out of the weed.

The range runs from the 🌊 Red Sea to 🇿🇦 South Africa, northern 🇦🇺 Australia and southern 🇯🇵 Japan. Here it is better called overlooked than rare, and the way to find one is to spend a dive somewhere with nothing on it.