As computer graphics are developing and digital films and animations are growing, we can meet cyber characters easily. Crowd behavior scenes in cyber underwater are used in game and entertainment industries. We should develop the techniques of 3D modeling and animation to create the cyber underwater using these cyber characters. Fish schooling or group moving in cyber underwater is a part of beautiful and familiar ecosystem. It is not so easy to present the behavior of fish crowd naturally as a computer animation. Thanks to development of computer graphics in entertainment industry, the numbers of digital films and animations is increased and the scenes of numerous crowd are shown to us. Though there are many studies on the techniques to process the crowd behavior effectively and the developments of crowd behavioral systems, there is not enough study on the development for an efficient crowd behavioral simulator. In this paper, we present a realistic and efficient Fish Schooling Behavior Simulator to create the contents of cyber underwater environment, which shows each type of fish behavior in cyber underwater smartly, and which generates the animating the behavior automatically, reducing the time and cost.