The Honeycomb Filefish (Cantherhines pardalis) is also known as the Wirenet Filefish and the Honeycomb Leather- jacket. They are unusual looking and are fairly shy fishes that are difficult to approach closely. The image below was obtained more by luck than anything else as the specimen moved around a rock at point blank range.
Filefish, also known as leatherjackets in Australia are closely related to Triggerfish and Pufferfish. Filefish are in the family Monacanthidae meaning one spine. Similar to Triggerfish, they have a prominent first dorsal spine which can be raised for defense or wedging themselves into a hole. Filefish obtain their name from their rough non overlapping scales which have small spikes on them.
The body is laterally compressed and the eyes are set high up and away from the mouth. The dorsal fin is divided into two parts, the forward dorsal fin being narrow and elongated and capable of folding back into a groove on the dorsal area. This can be seen in the images below. Coloration as with many file fish seems variable.
Juveniles are almost always seen displaying a solid brown color whereas the adults have a lighter brown pattern with thin blue streaks on the face and a honeycomb pattern on the main section of the body. The upper section of the nose is a light yellow color.
There is a characteristic white dot on the upper caudal area. Lightening of the main body color to a light grey which accentuates the honeycomb pattern has been recorded in Japan during mating but we have not sighted this behaviour ourselves. However at night we have noted the colouration below with a grey yellow background colour.
Honeycomb Filefish grow up to 25 centimeters but are usually between 18 to 20 centimeters in Tanzanian coastal waters.
HONEYCOMB FILEFISH IN THE WILD
The Honeycomb Filefish is a fairly shy fish and is hard to get close to. Usually when they sight a diver they go into hiding. If one does not move to quickly and drifts close to them , with some specimens it is possible to get fairly close to them. They will usually raise their dorsal fin when they sight a diver. If they want to make a quick getaway the fin is lowered while the fish accelerates off.
They are usually seen around the edges of the reef and seem to prefer areas with less dense coral growth. We have always seen them solitary and have never seen a pair together although once we sighted two juveniles together. They are reported to hide in Sargassum weed in some areas but we have never observed this. Sargassum weed is not that common in East Africa. In territorial disputes the males have been recorded to flick the main dorsal fin up and down as a warning signal to each other.
They are usually seen around the edges of the reef , sometimes on rubble areas and seem more common in the 15 to 18 meter depth range. Unusually their range stretches from the Eastern Atlantic up the East African Coast across to Southern Japan and down to Australia. They are replaced in Hawaii by Cantherhines sandwichiensis a similar looking species.
Research done in Japan indicates that they mainly eat Red Algae, sponges and some mollusks.
Honeycomb Filefish have been observed mating in Southern Japan. The Male follows the female, the female scouts out suitable areas to deposit the eggs. Once the female finds a suitable spot, usually in a toxic algae she thrusts her body into the algae. The male nuzzles the female and the eggs are laid and fertilized by the male. During the courtship process the male was noted to lighten his background coloration to a light grey. Laying the eggs in a toxic algae reduces the chances of predation of the eggs. The eggs are not cared for by the parents.
Honeycomb filefish are not often kept in private aquariums. Their diet of predominately red algae would make them difficult to feed and they are not sufficiently attractive to warrant attention. Given they are found in the Eastern Atlantic they must be capable of dealing with a large temperature range.