How to Identify Convict Tang

To identify Convict Tang (Acanthurus triostegus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

The body is typically pale white to silvery-grey, adorned with five to seven prominent, narrow, vertical black bands. A small black spot is often present at the base of the pectoral fin. The caudal fin is typically pale with a black margin.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

Five to seven vertical black bands on a pale body, Small black spot at the base of the pectoral fin, Scalpel-like spine on each side of the caudal peduncle

Dorsal fin

Single dorsal fin with IX spines and 22-26 soft rays, continuous and relatively low.

Tail fin

Lunate (crescent-shaped) caudal fin.

Pectoral fin

Pectoral fins are relatively large and fan-shaped, with 15-17 rays.

Distinctive fins

Anal fin with III spines and 19-22 soft rays. Pelvic fins with I spine and 3 soft rays. The characteristic retractable scalpel-like spine is located on each side of the caudal peduncle.

Identification Tips

1. 1

   Body Coloration and Bands

   Look for the distinctive pale body with 5-7 narrow, vertical black bands. This is the most reliable identification feature.

2. 2

   Pectoral Fin Spot

   A small, distinct black spot at the base of the pectoral fin is often present and aids in identification.

3. 3

   Caudal Fin

   The lunate (crescent-shaped) caudal fin with a dark margin is characteristic.

4. 4

   Size

   Adults typically reach a maximum standard length of about 26-27 cm (10-11 inches).

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