Where When How — N/D 2017 - J/F 2018
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Under The Sea Slender Filefish
Jayne Baker

One Of THe smAller And most beautiful treasures to be found on our reefs is the tiny slender filefish. divers will need a keen eye and some patience to find this little one, but those who like to scour the reefs for our smaller residents will often be rewarded with a sighting of this master of camouflage.

As the name suggests, the slender filefish belongs to the filefish family – a family group that comes in all sizes, shapes and colours. The larger members of the family, such as the scrawled filefish can reach sizes of 36 inches and have a scrawled iridescent blue pattern marking their bodies.

Other common members found on our reef include the white spotted filefish, orange spotted filefish, and we are occasionally fortunate enough to find unicorn or orange filefish. These members range from 8 -18 inches and have unique body shapes, patterns and colour phases. The slender filefish is the smallest of our filefish family here on our Turks and Caicos Island (TCI) reefs, clocking in around 1-2 inches long.

No matter their size, shape or colouration, all filefish have an elongated front dorsal spine that can be raised and lowered in response to threats, excitement or courtship rituals. The spine can be locked in place with a shorter, second spine behind it. filefish, along with triggerfish, also form a ‘super family’ called leather jackets, named for the rough texture of their skin. lore has it that fishermen would use the skin of these fish as sandpaper when they found one of them on their lines.

Being particularly shy, the best way to find one of the smallest, furtive filefish is to take your time looking through the soft corals in the 10-60 ft. depth range. Hanging vertically amongst the stalks of gorgonian coral, slender filefish can be almost impossible to see. A reticulated pattern covers its body, however this little fish can change its colours, patterns, and shadings dramatically to blend in with the soft corals it inhabits. This allows it ample cover from predators and divers alike. Unlike other members of its fish family, it is usually a solitary creature and divers will rarely find a pair of slender filefish on the same soft coral.

If you’re lucky enough to spy a slender filefish, you’ll notice their elongated snout and head, with a slender, diamond-shaped body that tapers back to a small, fan-like tail. An extendable belly appendage called a dewlap may or may not be visible extending underneath what we may think of as the ‘chin’ of fish. In juveniles the appendage is often retracted, but in adult fish it is often visible, making the fish appear larger than they are. Combined with the locking, front dorsal spine that crowns its head, this could be a mechanism used to discourage a potential predator.

Once you find a slender filefish, don’t take your eyes off of it for too long. In the second you take to turn around to point out your discovery to your dive buddy, that little, slender, shy fish will have moved on to another branch of coral and miraculously changed its patterns to disappear before your very eyes.