How to Identify Blue Damselfish

To identify Blue Damselfish (Pomacentrus alleni), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Predominantly electric blue body, often with a bright yellow to orange caudal fin. Some individuals may exhibit a yellowish tint on the posterior dorsal and anal fins. Juveniles may have a more intense blue coloration.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

Vibrant electric blue body coloration, Bright yellow or orange caudal fin, Small, oval-shaped body

Dorsal fin

Single dorsal fin with 13 spines and 13-15 soft rays. The spiny portion is continuous with the soft-rayed portion.

Tail fin

Forked caudal fin, typically bright yellow to orange.

Pectoral fin

Pectoral fins are clear to slightly yellowish.

Distinctive fins

Pelvic fins are typically blue, matching the body coloration.

Identification Tips

1. 1

   Coloration

   The most distinguishing feature is its brilliant electric blue body and contrasting yellow or orange caudal fin. This combination is quite unique among damselfish in its range.

2. 2

   Size

   Adults typically reach a maximum size of about 7-8 cm (2.8-3.1 inches) total length.

3. 3

   Fin Shape

   The caudal fin is distinctly forked, and the dorsal fin is continuous.

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