How to Identify Half Black Chromis

To identify Half Black Chromis (Chromis retrofasciata), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

The anterior half of the body is typically a pale, iridescent blue to silvery-white, transitioning abruptly to a dark brown or black posterior half, including the caudal fin. The demarcation line is usually quite sharp, running vertically just behind the pectoral fins. Some individuals may exhibit a yellowish tint on the anterior body or fins.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

Sharp bicolor pattern: pale anterior, dark posterior., Small, oval-shaped body., Forked caudal fin.

Dorsal fin

Single dorsal fin with 12 spines and 12-14 soft rays.

Tail fin

Deeply forked caudal fin, dark in coloration.

Pectoral fin

Transparent to slightly yellowish pectoral fins.

Distinctive fins

Pelvic fins are typically pale, matching the anterior body coloration.

Identification Tips

1. 1

   Coloration

   The most defining feature is the stark contrast between the pale anterior and dark posterior body. This 'half black' appearance is unmistakable.

2. 2

   Body Shape

   Its small, compressed, and oval body shape is typical of many Chromis species, but the coloration sets it apart.

3. 3

   Schooling Behavior

   Often observed in small to large schools, hovering above coral formations.

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