Indo-Pacific sailfish (Istiophorus platypterus)
With its huge, sail-like dorsal fin, long, pointed bill, and graceful, elongated body, the Indo-Pacific sailfish (Istiophorus platypterus) is one of the world’s most charismatic fish species. The body colouration is predominantly metallic blue, darker on the upperparts and lighter on the sides, with around 20 bluish vertical bars along the flanks, along with diffuse brown markings. The underparts are silvery white, while the sail-like first dorsal fin is darker blue, and marked with scattered small, dark, round spots. This striking fin is erectile, and provides stability when raised, but can be flattened into a groove along the back to reduce drag during bursts of speed. The Indo-Pacific sailfish’s additional fins are also distinctive, with slender, pointed pectoral fins, and a large, crescent-shaped caudal fin. The jaws of the Indo-Pacific sailfish extend into a slender bill, the upperpart of which is extremely long and bears a number of small, file-like teeth on the lower surface.