How to Identify Whiptail Mojarra

To identify Whiptail Mojarra (Gerres filamentosus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Silvery body, often with faint, irregular dark vertical bars or blotches on the flanks, which may fade after capture. Fins are typically translucent to dusky. The tip of the elongated second dorsal spine can be dark.

Scale type

ctenoid

Mouth position

inferior

Distinctive features

Highly protrusible mouth, forming a downward-pointing tube when extended., Deeply forked caudal fin., Elongated second dorsal fin spine, often extending beyond the posterior margin of the dorsal fin, sometimes reaching the caudal fin base in larger individuals., Lateral line complete and gently curved.

Dorsal fin

Dorsal fin with IX spines and 10-11 soft rays. The second dorsal spine is greatly elongated.

Tail fin

Deeply forked caudal fin.

Pectoral fin

Pectoral fins are long and pointed, reaching beyond the anus.

Distinctive fins

Anal fin with III spines and 7-8 soft rays. Pelvic fins are thoracic.

Identification Tips

1. 1

   Elongated Second Dorsal Spine

   The most distinguishing feature is the exceptionally long second spine of the dorsal fin, which is often filamentous and can be longer than the head.

2. 2

   Mouth Protrusion

   Observe the highly protrusible mouth, which can extend downwards to form a tube for sifting through substrate.

3. 3

   Body Coloration

   Silvery body with faint, often indistinct, vertical bars or blotches. This can help differentiate it from other mojarra species that might have more prominent markings.

4. 4

   Fin Ray Counts

   Accurate fin ray counts (D IX, 10-11; A III, 7-8) can be used for definitive identification, especially when examining specimens.

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