For realization of the marine ranching plan, partitioning off a part of the sea.is the most important subject. So authors developed an electrical screen and methods to control fish behavior and the electrical screen as stockade for marine ranching. This screen is naned '3 poles-2 potential type' and is able to shield electric field in the area of the screen. In this paper, a trial electrical screen screensystem is introduced and described its applicability in practice. This system consists of three parts of the electrical screen, the sensors and the controling instruments. The electrical screen was controlled in the room which was 100 meters away from the system. The items of sensing were depth, temperature, salinity, conductivity of sea water and also the electrical field of the barrier. And the electrical barrier is formed only when fish schooIs approach the screen. High efficiency of the electrical screen that controlled the fish behavior was proved by experiments which pastured 4,900 individuals of red sea breem (pagrus najor) in marine ranching area for 220 hours.