Today’s fish is one of the most stunning in the Caribbean! It has long been a favourite of divers due to its amazing colours and friendly disposition and is a real treat to see underwater.
The Scrawled Filefish, also known as the Scribbled Filefish, Broomtail or Leatherjacket, are the largest members of the Monacanthidae family. This family, the filefish, holds just over 100 species and while they are found all around the world over half are found in Australian waters. They are related to triggerfish, which is why they share some of their physical characteristics such as the spine on the tops of their heads.
What’s in a name?
The Scrawled filefish gets its name from the patterns along its body, looking like it’s been drawn all over with a bright coloured pen. The scientific name comes from 2 Greek and Latin words; aluterus meaning ‘not free’ or ‘detached’ and scriptus meaning ‘written’. We will explain the detached part later but the name filefish come from the rough skin that these fish have. Some sources say that the skins were used to sand boats and other wooden things in ancient times.
Habitat and distribution.
This species is circumtropical, meaning it can be found in tropical waters all around the world. While they can be found in the Red Sea and the Indo-Pacific, I found them to be more common in Caribbean waters, especially around Mexico and Belize. They can also be found pretty much everywhere from reefs, lagoons and pinnacles to wrecks and seagrass beds. They have also been observed in the open sea following the floating mats of sargassum weed. As a shallow water fish they are not regularly found much deeper than 30m but are most common in the sub 15m range.
Looks that kill.
The Scrawled filefish is an incredibly impressive fish to behold! They are a diamond shape with small pectoral, dorsal and anal fins but a large caudal fin (tail). This looks like an old broom when fully splayed, which is where the name Broomtail comes from. On the top of their heads there is a spine which can be raised and lowered based on the mood of the fish. This is also used to stick themselves into cracks and crevices or in the throat of something trying to eat it. It also has a lower spine on its chin to help with this, giving it the appearance of an anchor. One of the differences between filefish and triggerfish is that the fish needs to keep this spine erect whereas the triggerfish can lock them into a groove in their skulls. However, like triggerfish, they swim using the dorsal and anal fins on the back half of their bodies. They tend only to use their tail fins for a quick burst of speed.
The patterns on these fish are absolutely stunning and one of the reasons that photographers love them. They are a sandy gold colour with black spots all over them and vivid electric blue lines along their lengths. These blue lines really stand out when you see them underwater but much like an octopus or a cuttlefish they are able to change their background colouration very quickly, bleaching out or adding darker patches as it needs. Whilst working in public aquariums I noticed they would flash dark and pale when it was time to feed them. That means these colour changes may also be used for social interaction although I couldn’t find any sources to back up my hunch. There’s another project for our amateur scientists out there! Juveniles of the species are short and squat, with a background of bright yellow. The spots they have are much larger and darker and are not fixed, as they grow the spots will move to their adult locations.
Scrawled filefish are a solitary species but they can be found in pairs of very small groups when they breed. We have talked a lot about different breeding methods in this series and it’s time for another one! Female Scrawled filefish will lay their eggs on a surface such as a rock crevice or a depression in the sand where the male will then fertilize them. The adults will then guard the eggs until they hatch, both cleaning them and attacking any intruders that get close. Once the eggs hatch there is no parental care but they are looked after very well up to that point. It is the largest filefish species, growing to a maximum length of around 110cm and hitting around 2.5kg, although this doesn’t stop them using their colour changing skills to blend into their environment.
Life on the reef.
As these fish are found in so many different locations they can be observed acting differently in most of the places they are found. They are diurnal, meaning they are active during the day, and often found on their own. They like to hide amongst the reef, or wherever they are living, by changing their colour to blend into their surroundings; from bleaching to hide on sandy bottoms to increasing their blacker areas to hide in seaweeds.
The Scrawled filefish is omnivorous and will eat almost anything they can find using their strong jaws and specialised sharp teeth. This includes seaweeds and seagrasses, tunicates, gorgonians, sea anemones and small crustaceans and molluscs. They will also scavenge from larger things if they can find them.
I love these fish! I have been very fortunate to see them on almost every dive whilst in the Caribbean and on plenty in the Indo-Pacific. When I have seen them they have been hiding amongst the seaweeds or gorgonians with their large eyes roving around to watch as I approach. They would then appear from their hiding spaces and present side on in a way to seem much larger than they are and flashed colours at me. This makes sense as from the front on these fish seem small as they are laterally compressed, making them look thin. Taking pictures of them proved fairly easy, as they were presenting their fantastic patterns for me to shoot and allowing me to grab lots of different colour flashes.
The bottom line.
I travelled with Prodivers in Mexico, staying in Tulum, to see these fish. They always add a touch of magic to a dive and a splash of colour to your photos. It is worth approaching slowly and calmly to ensure you don’t spook them and just enjoy the show they will put on!