In actual there are no fish which fly like birds. If there were fish which actually “flew”, through the air like birds, they would apparently do it by flapping their “wings” or fins. The front fins of the flying fish are the wings. When flying it spreads the fins and holds them at an angle to the body. On occasions the fish spreads the rear fins as well.
The fish swims rapidly, a part of its body breaks the water surface and gets into air. It moves some distance gathering speed by moving the tail vigorously. Later it spreads fins and holds them tightly. The speed of its motion lifts it into air!
A flying fish may sail or glide for a distance of a few hundred meters and after some time drops back into water. Sometimes it hits the crests of the waves and moves its tail in order to pick up additional power while it is in flight. The flying fish does not just skin over the water. It can fly high enough to land on the decks of large ocean liners.