How to Identify Flyingfish

To identify Flyingfish (Exocoetidae), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Dorsal surface typically dark blue or greenish-blue, fading to silvery-white on the ventral side. This countershading provides camouflage from both aerial and underwater predators.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Greatly enlarged pectoral fins, often extending to or beyond the caudal fin base., Some species also possess enlarged pelvic fins, creating a 'four-winged' appearance., Lower lobe of the caudal fin is typically longer than the upper lobe, providing thrust for launching out of the water.

Dorsal fin

Single, relatively small dorsal fin, typically located posteriorly, often opposite the anal fin.

Tail fin

Deeply forked, heterocercal caudal fin, with the lower lobe significantly longer and stronger than the upper lobe, crucial for propulsion during glides.

Pectoral fin

Greatly enlarged and wing-like, extending laterally from the body. In 'two-winged' species, these are the primary gliding surfaces. In 'four-winged' species, the pelvic fins are also enlarged.

Distinctive fins

The primary distinguishing feature is the hypertrophied pectoral fins, which are rigid and used for aerodynamic lift during aerial glides. Pelvic fins can also be enlarged in some genera (e.g., Cypselurus, Hirundichthys) to form a second pair of 'wings'.

Identification Tips

1. 1

   Pectoral Fin Size

   The most obvious characteristic is the exceptionally large pectoral fins. Observe if they extend past the dorsal fin origin or even to the caudal fin base.

2. 2

   Pelvic Fin Size

   Distinguish between 'two-winged' (only pectoral fins enlarged) and 'four-winged' (both pectoral and pelvic fins enlarged) species. In four-winged species, the pelvic fins are typically located abdominally and are also wing-like.

3. 3

   Caudal Fin Shape

   Note the deeply forked caudal fin with a distinctly longer lower lobe, a key adaptation for generating thrust for flight.

4. 4

   Body Coloration

   Look for the characteristic dark blue/greenish-blue dorsal and silvery-white ventral countershading.

5. 5

   Presence of Barbels

   Some juvenile flyingfish (e.g., in the genus Exocoetus) possess prominent barbels, which are lost as they mature. This can be a key identifier for younger individuals.

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