|Platybelone argalus argalus|
Keeltail needlefish, like all needlefish, closely resemble North American freshwater gars (family Lepisosteidae). It is most recognized by the large, flat keel-like structures running on either side of the tail. They have 12 to 15 rays on their dorsal fins, and 17 to 20 rays on their anal fin. Keeltail needlefish have gill-rakers, their caudal peduncles have lateral keels, with a lateral line running ventral to it, and grow up to 50 cm long  The keeltail needlefish's top jaw is also smaller than the lower one.
Distribution and habitat
Keeltail needlefish are found in the western Atlantic ocean between North Carolina and Brazil, this includes the Gulf of Mexico, the Bahamas, and the Caribbean sea. In the Indian ocean, they are known off of east Africa,with range continuing into the Pacific reaching the Hawaiian islands and continuing north to the Ogasawara Islands. Keeltail needle fish have also been found around the Arabian Peninsula, in the Red sea and Persian gulf  They usually occur offshore and are abundant around islands. Some of the most recognized subspecies are Platybelone argalus platura, most common in the Red Sea and Persian Gulf;Platybelone argalus platyura, known from the rest of the Indo-pacific; and Platybelone argalus argalus from the Atlantic.
They school in sheltered parts of reefs, feeding mainly on smaller fish. Keeltail needlefish are egg-laying, attaching their eggs to floating objects with specialized tendril-like structures on the egg's surface.
There are currently seven recognized sub-species though it has been proposed that several of them be elevated to the status of full species:
- Platybelone argalus annobonensis Collette & Parin, 1970 (Annobon keeltail needlefish)
- Platybelone argalus argalus (Lesueur, 1821) (Keeltail needlefish)
- Platybelone argalus lovii (Günther, 1866)
- Platybelone argalus platura (Rüppell, 1837)
- Platybelone argalus platyura (E. T. Bennett, 1832) (Keeled needlefish)
- Platybelone argalus pterura (R. C. Osburn & Nichols, 1916) (Baja California keeltail needlefish)
- Platybelone argalus trachura (Valenciennes, 1846)
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