Latin name

Siganus luridus

Other name

Squaretail rabbitfish

Identification

The body of the Dusky Spinefoot is oval, elongated. Its depth is 2.1-2.8 times its standard length. The jaws have a single row of incisor-like teeth, each with 1 or 2 lateral projections. The antebrachial angle is 87-97 degrees. Anterior nostril with a long wide flap covering the posterior nostril when it is down. Uneven incision of the cheeks. The midline of the thorax is free of scales between the pelvic ridges. This fish has venomous spines on its fins. 

Features of fish fins

The dorsal fin has 13-14 spines and 10 soft rays, while the anal fin has 7 spines and 9 soft rays. The caudal fin is truncated. The anterior spines of the median fins are thin and sharp, while the posterior spines are thick.

Fish colouring

The coloration of the Dusky Spinefoot varies, usually from olive green to dark brown with a mottled pattern. The pectoral fins are hyaline yellow and the caudal fin has dark stripes.

Distribution

Widespread in the western Indian Ocean: Persian Gulf; Red Sea and East Africa to islands in the western Indian Ocean. Immigrants to the Mediterranean through the Suez Canal.

Habitat

A subtropical marine species. It inhabits depths from 2 to 40 m (6 feet 7 inches and 131 feet 3 inches) in waters over hard substrates such as coral and rocky reefs.

Size

This species reaches a maximum total length of 30 cm (12 inches), although 20 cm (7.9 inches) is more typical.

Behavior

Found in small schools in very shallow water, close to the bottom. They prefer hard bottoms of compacted sand with stone or coral fragments. Individuals and groups of 3-4 adults have been observed. They may stop suddenly and spread their fins (dorsal, anal, and pelvic), exposing many venomous spines to potential predators. 

Food and feeding habits

Feeds on a wide range of bottom dwelling algae. 

Reproduction

Dusky spinefoot larvae remain near the water surface. Feeding on phytoplankton and zooplankton begins 3 days after hatching.

Fishing

The species is of minor commercial interest.

Relationship with a person

Venomous. A food fish that is sometimes poisonous. May not adapt well to captivity. The barbs of this fish are painful to sting, making it a danger to careless swimmers, although its venom is not fatal to humans.