First, it must be noted that Beautiful Fish Screensaver is NOT a real screensaver, it is actually an application. HOWEVER, its realistic effects and vivid sounds will bring you a different experience. You will feel that your mac screen showing real live fishes swimming in the water. There are 8 kinds of fish and 3 living environments for fishes, you are free to choose the type and quantity of fish and environment. Give it a try and see what feeling it can bring you. Enjoy it quickly!