When you tap the fish, it will sortie and attack the enemy.
Due to the cost of the fish sortie and the maximum cost, the timing of the sortie is important. As soon as the fish touches the enemy or white, it begins attacking it. As a result of the attack, the enemy's castle or enemy will be damaged. Inflicting damage and reducing the health of the enemy's castle to 0 clears the game. Meanwhile, if your castle's health reaches 0, you can start over as many times as you like. Since there is no health indicator other than the castle, you have to be careful when the fish fall.