How to Identify Dusky Spinefoot

To identify Dusky Spinefoot (Siganus luridus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Highly variable, typically mottled greenish-brown to dark brown, often with irregular pale spots or lines. Can rapidly change color to a pale, almost silvery hue, especially at night or when stressed. Juveniles may have more pronounced patterns. The belly is usually paler.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Small, rabbit-like mouth with incisor-like teeth, Venomous spines in dorsal, anal, and pelvic fins, Cryptic coloration that can change rapidly, Deeply forked caudal fin in adults

Dorsal fin

13 spines, 10 soft rays. The spines are stout and venomous.

Tail fin

Deeply forked in adults, truncate to slightly emarginate in juveniles.

Pectoral fin

16-18 rays, typically clear to yellowish.

Distinctive fins

Pelvic fins have 1 spine, 3 soft rays, and 1 spine (I,3,I), a characteristic of the Siganidae family. All fin spines are venomous.

Identification Tips

1. 1

   Body Coloration

   Observe the mottled greenish-brown to dark brown body, often with irregular pale spots or lines. Note its ability to rapidly change color, especially when stressed or at night (becomes pale and blotchy).

2. 2

   Mouth and Teeth

   Look for the small, rabbit-like mouth with incisor-like teeth, adapted for grazing on algae.

3. 3

   Fin Spines

   Identify the stout, venomous spines in the dorsal, anal, and pelvic fins. The pelvic fin formula (I,3,I) is a key family characteristic.

4. 4

   Caudal Fin

   In adults, the caudal fin is deeply forked, distinguishing it from some other rabbitfish species with truncate or emarginate tails.

Explore Dusky Spinefoot