Identification
The Keeltail Needlefish is a shimmering, silver javelin of the surface waters. Reaching up to 45 cm, its most defining field mark is the "keel"—a distinct horizontal flattening of the tail base (caudal peduncle) that looks almost like a pair of tiny stabilizer wings. Look for its elongated, tweezer-like jaws bristling with fine teeth and its vibrant bluish-green dorsal coloration, which fades into a brilliant metallic silver along the flanks. Unlike the larger Crocodile Needlefish, the Keeltail remains slender and possesses that namesake flattened tail base which is unmistakable upon close inspection.
Habitat & Range
This circumtropical wanderer is found in the warm upper layers of the Atlantic, Indian, and Pacific Oceans. You’ll typically spot them hovering just inches below the surface in lagoons, over seaward reefs, or in the open blue. They are masters of the "epipelagic" zone, rarely venturing more than a few meters deep, preferring the sun-drenched interface between air and sea.
Behaviour
To observe a Keeltail is to see a study in stillness followed by explosive speed. They often drift motionless, mimicking a piece of flotsam, until startled. When threatened by a predator from below, they perform a spectacular "skitter," leaping from the water and vibrating their tails against the surface to skip away like a flat stone. They are generally solitary or found in loose, small groups, patrolling the surface with a quiet, predatory grace.
Diet
These are precision ambush hunters. They target small schooling fishes and floating crustaceans, using their needle-like beaks to snatch prey with a lightning-fast side-swiping motion. Their narrow profile and silver belly make them nearly invisible to prey looking up from below against the glare of the sun.
Fascinating Fact
If you were to see the skeleton of a Keeltail Needlefish, you might think it had been dyed for a movie! Their bones are a striking, vivid emerald green. This startling hue is caused by the presence of biliverdin, a natural bile pigment that accumulates in their skeletal structure.