Before the game starts, all players receive a “fish” tile which indicates the color of their fish. Then the players each receive a “coral” card which they place, coral side up, in front of them and which will serve as the starting point for their school of fish.
Shuffle the rest of the cards and divide them into four approximately equal stacks, fish bone side up. Turn over the top card of each of the stacks and place it in front of its stack.
Throughout the game, the players will each form a school of fish in front of them. They must all try to ensure that at the end of the game, their own color of fish is in the majority
On a player's turn they will choose two cards from among the four visible cards from the stacks. Then they will place one of them in their school of fish and the other in an opponent’s school. At the end of their turn they will flip over two cards from the stacks so that there are always four cards visible.
There are different kinds of cards - coral, fish, octopus, and shark - which are placed adjacently (not diagonally) to one or more cards with additional rules depending on the type of card.
The game ends when three of the stacks are finished. Players then each count their points:
- 1 point for each fish of their color present in their school as well as in their opponents’ schools.
- 3 points if in their own school of fish they have a majority of their own color of fish.
- 1 point for each octopus in their school.
- 2 points for the player with the most sharks in his school of fish
The player who has earned the most points wins the game. In case of a tie, to determine the winner: the one with the most fish in his school wins the game.