How to Identify Dusky Damsel

To identify Dusky Damsel (Stegastes adustus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Adults are typically dark brown to black, often with a bluish or purplish sheen, particularly on the scales and fins. Juveniles may display a mottled or banded pattern, which fades as they mature. Some individuals may have a pale spot at the base of the pectoral fin. The eyes are relatively large and dark.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

Robust, compressed body, Dark, often iridescent coloration, Small, ctenoid scales, Continuous dorsal fin with prominent spines, Forked caudal fin

Dorsal fin

Single, continuous dorsal fin with 12 spines and 14-17 soft rays. The spiny portion is longer than the soft-rayed portion.

Tail fin

Moderately forked caudal fin, typically dark.

Pectoral fin

Pectoral fins are relatively large and rounded, often with a pale spot at their base.

Distinctive fins

Anal fin with 2 spines and 12-14 soft rays. Pelvic fins are thoracic, with 1 spine and 5 soft rays.

Identification Tips

1. 1

   Coloration

   Look for the overall dark brown to black body color, often with a subtle blue or purple iridescence. Juveniles may have faint banding.

2. 2

   Body Shape

   Note the robust, compressed body typical of damselfishes.

3. 3

   Habitat

   Observe its preference for rocky intertidal zones, shallow reefs, and areas with algal growth.

4. 4

   Behavior

   Its highly territorial nature and aggressive defense of its chosen patch are strong indicators.

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