Fourwing Flyingfish

The Fourwing Flyingfish (Hirundichthys affinis) is a member of the flyingfish family Exocoetidae, distinguished from many relatives by having both enlarged pectoral and enlarged pelvic fins, the trait that gives "four-winged" flyingfish their name. Both pairs of fins extend at least to the middle of the dorsal and anal fins, providing extra lift for exceptionally long, stable glides. The species is found in the tropical and subtropical Atlantic, ranging from Guinea to Angola in the eastern Atlantic and from the Gulf Stream off Virginia and the northern Gulf of Mexico south to northern Brazil in the west, including the wider Caribbean Sea. It reaches a maximum length of about 33 cm and is most abundant seasonally between December and June.

• Slender, torpedo-shaped body reaching a maximum of about 33 cm, commonly around 24 cm
• Both pectoral and pelvic fins are greatly enlarged, forming two pairs of "wings," the defining four-winged flyingfish trait
• Pectoral fins are grey with pale triangular crossbands and extend nearly to the base of the tail fin
• Dark, iridescent blue-black back grading sharply to silvery-white below
• Deeply forked tail with a longer lower lobe
• Distinguished from two-winged flyingfish (such as the Spotfin or Sailfin Flyingfish) by its additional pair of enlarged pelvic "wings"

Fourwing Flyingfish inhabit warm, open surface waters of the tropical and subtropical Atlantic Ocean. Its range spans the eastern Atlantic from Guinea to Angola and the western Atlantic from the Gulf Stream off Virginia and the northern Gulf of Mexico south through the Caribbean Sea to northern Brazil. Like other flyingfish, it stays almost entirely at the ocean surface, generally over deep offshore water rather than around reefs or estuaries, and its distribution tracks warm current systems such as the Gulf Stream. Abundance is markedly seasonal in parts of its range, with the species common between December and June and comparatively scarce from July to November, likely tied to spawning and current patterns.

Fourwing Flyingfish glide using both pectoral and pelvic fins simultaneously, generating extra lift that allows for notably long and stable glides compared with two-winged flyingfish species. An individual accelerates underwater with rapid beats of the elongated lower tail lobe before breaking the surface and spreading all four fins to soar over the waves. This gliding behavior is chiefly a defense against fast-swimming predators such as tuna and dolphinfish that hunt from below. The species feeds on planktonic organisms at the surface and shows a pronounced seasonal abundance pattern in the western Atlantic, closely tied to its reproductive cycle. Spawning occurs in open water, with eggs bearing adhesive filaments that attach to floating sargassum or debris.