Each fish species can move either horizontally or vertically. Horizontal fish can move to the left, the right or both. Vertical fish can move up, down, or both. Fish can also be stationary. The starting position of the horizontal species can be constrained to the top, bottom or middle of the screen. Vertical species can be restricted to the left, right or middle of the screen.
The miniature desktop area shows how the fish will behave on the real desktop with the motion options currently selected.