How to Identify Pacific Viperfish

To identify Pacific Viperfish (Chauliodus macouni), look at these key features.

Physical Characteristics

Body shape

eel-like

Coloration

Iridescent dark silver to black, often with a metallic sheen. The photophores emit various colors, primarily blue-green.

Scale type

none

Mouth position

superior

Distinctive features

Extremely long, fang-like teeth, particularly the first two teeth in the lower jaw, which are so long they curve back over the head when the mouth is closed., A long dorsal fin ray with a photophore at its tip, used as a lure., Numerous photophores arranged in rows along the ventral side of the body and on the head., Large eyes, adapted for low light conditions, though vision is likely limited in the deepest parts of its range., A chin barbel, though less prominent than in some other deep-sea fish.

Dorsal fin

Single dorsal fin located mid-body, with a prominent elongated first ray bearing a photophore. Typically 5-7 soft rays.

Tail fin

Forked caudal fin.

Pectoral fin

Small, located low on the body, typically with 10-13 rays.

Distinctive fins

Adipose fin present, small. Pelvic fins are abdominal, with 7-8 rays.

Identification Tips

1. 1

   Teeth

   The most striking feature is the disproportionately long, needle-sharp teeth, especially the two anterior lower jaw teeth that extend past the upper jaw and curve back towards the eyes when the mouth is closed. These teeth are translucent.

2. 2

   Photophores

   Observe the distinct patterns of photophores along the ventral side of the body and on the head. A prominent photophore is also present at the tip of the elongated first dorsal fin ray.

3. 3

   Body Shape

   Its elongated, slender, and somewhat compressed body, combined with its dark, iridescent coloration, is characteristic.

4. 4

   Size

   Adults typically reach a maximum standard length of about 30-35 cm (12-14 inches).

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