They move the same as usual but start one square further forward.
When they reach 3 squares from the edge of the board they become queens.
Rooks are called boats, Knights are just horses but both work as normal.
The King is still a King and moves the same with the exception of it's first move where it can move like a horse.
Queens can only move one space on a diagonal with one exception. Provided the fish in front of it moves first it can jump 2 squares forwards on it's first go. But it is defiantly one of the weakest pieces on the board.
Bishops I've only heard referred to as "this one" again only has a one square range but can go any diagonal and straight forward. Like a combination of Queen and Fish.