Scrawled Filefish, Aluterus scriptus
The Scrawled Filefish, Aluterus scriptus, whose common Spanish name is Lija Trompa is a member of the Filefish or Monacanthidae Family, known collectively as “Lijas” in Mexico.
The Scrawled Filefish have very compressed elongated oval bodies. They are olive brown to gray in color with irregular blue spots, short lines, and black spots covering their head and body. They have the ability to change color to match their surroundings. Upon death, their coloring transitions into a bland and uniform tan. Their head has a strongly concave upper and lower profile and features a long pointed snout, a small centrally located upturned mouth, and small beady eyes located high on the back on the head. Their caudal fin base is deeper than it is long; the fins are relatively long and rounded with a ragged rear margin. They have two dorsal spines, the first of which is long and slender and is located directly over the eyes; it can be locked in position by the second smaller spine. When threatened, the Scrawled Filefish will dive quickly into a crevice in the reef, wedge themselves into the shelter by erecting and locking their first dorsal spine and another spine located on their belly. This behavior is also used when they rest on the reef at night. They lack pelvic fins. Their body is covered with small scales and small hairs creating a coarse sandpaper-like texture.
The adult Scrawled Filefish are benthic, being found at depths up to 400 feet, and inhabit coral and rocky reefs; the juveniles are pelagic and found in and around floating debris at large distances from land. They have a wide global distribution which includes the Eastern Atlantic (entire west coast of Africa), the Western Atlantic (Canada to Brazil), the Eastern Pacific (Sea of Cortez to Columbia), and the Western Pacific (southern Japan to Australia’s Great Barrier Reef). In Mexican oceanic waters they are found throughout the Gulf of Mexico and in the Pacific from Magdalena Bay south along the west coast of Baja, in the southern two thirds of the Sea of Cortez, and along the coast of the mainland south to Guatemala.
The Scrawled Filefish are secretive fish that hide in caves. They are omnivorous and feed on algae, anemones, gorgonians, sponges, and tunicates. In turn, they are preyed upon by larger fish including Dorado, Coryphaena hippurus, and Bluefin Tuna, Thunnus thynnus. They reach a maximum length of 110 cm (43.3 inches) and a maximum weight of 2.5 kg (5.5 pounds). They breed in groups consisting of one male and two to five females. The females lay demersal eggs in safe areas, such as depressions in the sand, and the eggs are then fertilized by the males. Both the males and the females will guard these fertilized eggs from predators. Upon hatching, the females will care for the young.
The Scrawled Filefish is easily confused with the Unicorn Filefish, Aluterus monoceros (convex upper and concave lower head profile, numerous blotches, straight caudal fin).
The Scrawled Filefish are considered to be game fish in some parts of the world but in Mexico they are rare and of limited value, thus normally a “catch and release.” They are reported to contain Ciguatera Toxin making them a poor food choice. They are collected and sold for the aquarium trade at a modest level. As they are truly gorgeous when alive and a relatively shallow water slow-moving species, they are often the subject of underwater photographers.