Wisko and the wahoo fish are only mentioned in the first book in Shark Wars and they're mysteriously odd. Wisko is there leader. Goblin called this game the Tuna Roll.
It's when the sharks go after the wahoo fish and eat them. There are 2 teams in all. The winning team is served dinner from the losing team. Wisko then gives a speech about the game and how good or bad it was.
Title: is the leader of the wahoo gang
(the wahoo fish)