The fastest fish in the world is a fish-sailer. There are two types of fish: Istiophorus platypterus, who lives in the Indian Ocean, and Istiophorus albicans, which is found in central and western Pacific Ocean. That fish-Pacific sailfish can move in water with a speed of 100 km / hour.But what makes sailing the fastest beings in the water? Firstly - it is their fin. If the fish swims at high speed, the dorsal fin is hidden in the recess on the back, but at a sharp turn, he "pulled out" so that a sailboat can be a very sharp turn, chasing prey.Second, it helps their sailboats and a streamlined aerodynamic (or more appropriate here - akvadinamicheskoe) body covered with small grooves of zubchikoobraznyh outgrowths. These furrows retained water ivyhodit that is not the body of the sailboat, and "water film", clinging to him in contact with water, greatly reducing friction. Also, far from outstanding pointed jaw fish can achieve the effect of turbulence and the tail fin, narrow crescent-shaped and even oscillates with small amplitude, but does so with great speed. Source