How to Identify Scrawled Filefish

To identify Scrawled Filefish (Aluterus scriptus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Highly variable, typically mottled shades of brown, green, grey, or olive, often with irregular blue, black, or yellow spots and lines (scrawls) over the body. Can rapidly change color to match its surroundings. The caudal fin is often yellowish.

Scale type

none

Mouth position

terminal

Distinctive features

Elongated, laterally compressed body, Small, upturned mouth with strong teeth, Rough, sandpaper-like skin (no scales in the traditional sense), Single, prominent, erectile dorsal spine that can be locked upright, Second dorsal spine greatly reduced or absent, Long, fan-like dorsal and anal fins set far back on the body, Long, rounded caudal fin

Dorsal fin

First dorsal fin consists of a single, strong, erectile spine followed by a much smaller, rudimentary second spine (often embedded). Second dorsal fin is long and soft-rayed (typically 46-49 rays).

Tail fin

Long, rounded, and fan-like (typically 12 rays).

Pectoral fin

Small and rounded (typically 13-15 rays).

Distinctive fins

Pelvic fins are absent, replaced by a dewlap-like structure or a small, rough spine at the ventral midline.

Identification Tips

1. 1

   Body Shape and Coloration

   Look for the elongated, compressed body with highly variable, mottled patterns of spots and lines (scrawls). The ability to rapidly change color is a key indicator.

2. 2

   Dorsal Spine

   Observe the single, prominent, erectile dorsal spine located just above the eyes. This spine can be locked upright, giving the fish its 'file' appearance.

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