How to Identify Threadfin Butterflyfish

To identify Threadfin Butterflyfish (Chaetodon auriga), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

The body is predominantly white to yellowish-white anteriorly, transitioning to yellow posteriorly. A prominent black band runs diagonally from the forehead through the eye. Another broad, dark diagonal band extends from the anterior dorsal fin to the anal fin. The posterior part of the body and the dorsal and anal fins are bright yellow. A distinctive black spot is often present on the soft dorsal fin, though its prominence can vary. The caudal fin is yellow with a submarginal black band.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

Elongated, thread-like filament extending from the posterior part of the soft dorsal fin (more pronounced in adults)., Diagonal black band through the eye., Diagonal black band from the dorsal fin to the anal fin., Yellow posterior body and fins., Often a black spot on the soft dorsal fin.

Dorsal fin

11-13 spines, 22-25 soft rays; the last few soft rays are elongated into a distinctive filament.

Tail fin

Truncate to slightly emarginate.

Pectoral fin

15-16 rays.

Distinctive fins

The elongated dorsal filament is the most distinguishing fin feature.

Identification Tips

1. 1

   Dorsal Filament

   Look for the characteristic elongated, thread-like extension from the soft dorsal fin, especially in adult specimens. This is a key identifier.

2. 2

   Color Pattern

   Observe the distinct diagonal black band through the eye and the broader diagonal black band across the body. The yellow posterior body and fins are also very characteristic.

3. 3

   Black Spot

   Note the presence of a black spot on the soft dorsal fin, though its intensity can vary.

4. 4

   Body Shape

   Its laterally compressed, disc-shaped body is typical of butterflyfishes.

Explore Threadfin Butterflyfish