Some reef fish are hard to miss and still easy to overlook. The scrawled filefish can be nearly a meter long, yet it drifts so slowly and turns so flat to the reef that divers swim right past it. When you do notice one, it looks as though someone has taken a bright blue pen to an olive-gray fish and scribbled all over it, which is exactly how it got its name.

It is one of the largest filefishes in the world and is found in every tropical ocean, including the reefs around Punta Cana. It is not a fish you see on every dive, which is part of the fun: a scrawled filefish gliding past a sea fan is a sighting divers remember.

Quick Facts

Name: scrawled filefish, Aluterus scriptus; family Monacanthidae (filefishes)
Size: commonly around 55 cm (22 in); the largest recorded reached about 110 cm (43 in)
Diet: algae, seagrass, hydrozoans, gorgonians (sea fans and sea rods), colonial anemones and tunicates
Depth: recorded from 3 to 120 m, most often 3 to 20 m (10 to 65 ft)
Range: circumtropical; in the western Atlantic it occurs through the Caribbean, Bahamas and Florida
Status: listed as Least Concern by the IUCN

How to Recognize a Scrawled Filefish

Start with the shape. The body is long, oval and very flat from side to side, with a small, upturned mouth at the end of a long, sloping snout. A single slender spine sits on top of the head, above the eye, and usually lies folded back. The soft dorsal and anal fins are set far back on the body and ripple to move the fish along. The tail is the giveaway: long, broom-shaped and rounded, often with a ragged rear edge.

The base color ranges from pale gray to olive brown and can shift to match the surroundings. Over it run irregular bright blue lines and spots, mixed with small black dots. The skin is covered in tiny rough scales, so it feels like sandpaper, and that file-like texture gave the whole family its name.

Look-alikes on Caribbean reefs:

Orange filefish (Aluterus schoepfii): similar long, flat shape, but covered in orange spots instead of blue scribbles, with a short tail.
Unicorn filefish (Aluterus monoceros): deeper-bodied and pale gray or brown, with fine dark spotting and no blue markings.
Whitespotted filefish (Cantherhines macrocerus): much smaller, chunkier, and brown to orange with white spots.

If it has blue scribbles and a long broom tail, it is a scrawled filefish.

Behavior: Slow Grazer With a Locking Spine

Scrawled filefish are usually seen alone, cruising slowly over the reef and stopping to pick at food. They are true reef grazers, eating algae and seagrass but also animals that most fish avoid: sea fans and other gorgonians, colonial anemones, tunicates and hydrozoans, the group that includes fire coral. Watching one feed among the sea fans and soft corals is one of the best ways to find it.

That head spine is its main defense. When threatened, the filefish dives into a crevice and raises the spine, which is locked upright by a second, smaller spine behind it, and extends a spine on its belly at the same time. Wedged in place, it is very hard for a predator to pull out. It uses the same trick to stay secure while resting at night.

The young have a different lifestyle. Juveniles drift in the open ocean under floating seaweed and debris, sometimes for a long time, and swim head-down with their tails undulating so they look like a piece of weed. Adults breed in small groups of one male and several females. The female lays eggs in a sheltered spot such as a depression in the sand, the male fertilizes them, and the eggs are guarded until they hatch.

Where to See Scrawled Filefish in Punta Cana

On our local reefs the scrawled filefish is an occasional sighting rather than a regular one. Adults tend to favor deeper reef edges and drop-offs, so your chances improve on dives like Anchor, at 19 m (62 ft), and on the outer edges of Rock City. Scan the areas with plenty of sea fans and soft corals, where they come to feed.

Further afield, The Wall at Catalina, a drop-off to 30 m (100 ft), is exactly the kind of steep reef where large filefish cruise along the slope. You will also find the scrawled filefish on our species guide.

Photography Tips

Approach slowly and from the side. Scrawled filefish are not easily startled, and a calm diver can often stay with one for a while.
Shoot it side-on to get the whole flat body and the broom tail in the frame. That is where the scribbles show best.
Use a strobe or a good light at close range: the blue lines look dull in ambient light at depth and pop with a little light.
If it turns its narrow edge toward you, wait. It will usually turn side-on again as it feeds.
Never chase one into a crevice. Once it locks its spine in, the encounter is over for both of you.

Frequently Asked Questions

Are scrawled filefish dangerous?

No. They are slow, shy grazers with no venom and no interest in divers. The head spine is purely defensive.

How big do scrawled filefish get?

Most adults are around 55 cm (22 in), and the largest recorded reached about 110 cm (43 in), which makes it one of the biggest filefishes.

Can you eat scrawled filefish?

It is caught as food in some places, but cases of ciguatera poisoning have been reported from eating it, according to the Florida Museum and FishBase. It is not worth the risk.