The color of fish changes if you click it. Together the color of clock will become gray for couple of seconds. In case you keep simply clicking fish, it will go away.
The app works with Nokia 5800 XpressMusic, N97, N97 Mini, X6, 5228, 5230, 5233, 5235, 5530 XpressMusic, N8, E7, C6 and C7. You can download this widget based flash app from the following link. Enjoy fish!