How do flying fishes use their pectoral fins during gliding flight?

Flying fishes (family Exocoetidae, order Atheriniformes) do not flap their fins to fly; instead, they use their enlarged pectoral fins to glide above the water's surface as a means of escaping predators.12

While swimming underwater, the fish keeps its fins folded tightly against its streamlined body to build speed. Upon breaking the surface, the fish expands its winglike pectoral fins. These fins provide the necessary lift to raise the fish's body above the water. While the pectoral fins are spread, the fish continues to gain thrust by rapidly beating its still-submerged, asymmetrical tail.132

In some species, the pelvic fins also expand once the entire body is airborne, further assisting in the glide. The fish remains in the air until its forward velocity is lost, at which point it may drop back into the water and use its tail to scull and pick up speed for subsequent glides.123