How to Identify Squirrelfish

To identify Squirrelfish (Holocentrus adscensionis), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Predominantly red to reddish-orange dorsally, fading to silvery-white ventrally. Often has faint longitudinal stripes or lines along the flanks. Fins are typically reddish, with the dorsal fin often having white tips on the spines.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

Large eyes, adapted for nocturnal vision., Prominent, spiny dorsal fin., A sharp, venomous spine on the preopercle (cheek bone)., Rough, ctenoid scales., Forked caudal fin.

Dorsal fin

Single dorsal fin, deeply notched, with 11 spines followed by 12-15 soft rays. The anterior spines are typically longer.

Tail fin

Deeply forked caudal fin.

Pectoral fin

Pectoral fins are relatively short, with 13-15 rays.

Distinctive fins

Pelvic fins are thoracic, with 1 spine and 7 soft rays. Anal fin has 4 spines and 8-10 soft rays, with the third anal spine being notably long and robust.

Identification Tips

1. 1

   Coloration

   Look for the characteristic reddish body, often with faint stripes. The intensity of red can vary.

2. 2

   Eyes

   Its very large eyes are a key indicator of its nocturnal habits.

3. 3

   Preopercular Spine

   Carefully observe the prominent, sharp spine on the lower margin of the gill cover (preopercle). This is a crucial distinguishing feature.

4. 4

   Dorsal Fin

   Note the deeply notched dorsal fin with strong spines, particularly the longer anterior ones.

5. 5

   Anal Fin Spines

   The third anal fin spine is typically very robust and long, often longer than the fourth dorsal spine.

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