How to Identify Barreleye fish

To identify Barreleye fish (Macropinna microstoma), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Generally dark brown to black, with a transparent head dome. The eyes are typically green due to a yellow filter pigment.

Scale type

none

Mouth position

terminal

Distinctive features

Transparent, fluid-filled dome on its head, Tubular, upward-pointing eyes (can rotate forward), Small, terminal mouth, Large, paddle-like pectoral fins

Dorsal fin

Single dorsal fin, relatively small and set far back on the body.

Tail fin

Forked caudal fin.

Pectoral fin

Large, broad, and paddle-like, positioned horizontally.

Distinctive fins

Pelvic fins are also large and horizontally oriented, aiding in stability and maneuvering in the water column.

Identification Tips

1. 1

   Transparent Head

   The most striking feature is the transparent, fluid-filled dome covering its head, through which its eyes are visible. This dome is often damaged or lost during capture, leading to earlier misinterpretations of its anatomy.

2. 2

   Tubular Eyes

   Its large, tubular eyes are typically directed upwards, allowing it to scan for prey silhouetted against the faint light from above. These eyes can rotate forward when the fish is feeding.

3. 3

   Olfactory Organs

   The two small, dark indentations above its mouth are not eyes, but rather its olfactory organs (nares), used for sensing chemicals in the water.

4. 4

   Pectoral Fins

   Possesses large, horizontally oriented, paddle-like pectoral fins that are used for precise maneuvering and maintaining a stable position in the water column.

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