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Mediterranean invasive species factsheet

FISHES

Reproduction Common name: Marbled spinefoot

olive-green to brown colour
identification Caudal fin forked

Scientific Name:
Siganus rivulatus
Picture

Key identifying features
This medium-sized fish has an ellipsoidal, Brief history
compressed body covered with small scales Body more elongated with fine
yellow stripes
embedded within the skin. It grows to a length of up
to 27 cm, commonly 5–25 cm.

The dorsal fin, with 13–14 spines and 10 soft rays,
begins above the pectoral fin base, and the first
dorsal spine points forward. Key taxonomical
groups of 50 to several hundred individuals, feeding
features for this species’ identification are pelvic fins
mainly green and red algae, such as Ulva spp. and
with two stout spines connected by a membrane to
Hypnea spp., and seagrasses (Posidonia oceanica).
the abdomen, and the forked tail fin. There are 7
spines in the anal fin with 8–10 soft rays. The anterior Reproduction
spines of the median fins are slender, whilst the
The spawning season lasts from May to September.
posterior spines are stout, all of the spines being
venomous. The mouth is small with distinct lips.

Body colour is brown to grey green, and light-brown
to yellow on the belly. There are fine, often faint,
yellow-gold stripes on the lower half of body. At night
or when frightened, the colour is very mottled, with
six diagonal bars across the flank.

Field identification signs and habitat
The marbled spinefoot lives in shallow waters,
preferring hard bottoms of compacted sand with rock,
usually covered with vegetation. Adults live in small

Siganus rivulatus. Photo: P. Francour Siganus luridus. Photo: B. Daniel

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