The correct answer is:
The captain tells Stefano that colomber is a fish rather a shark that all sailors fear above all. And that it will follow him until it has devoured him.
In the story "The Colomber," by Dino Buzzatti, the boy Stefano Roi joins his father, who is a sea captain, on his boat and notices an unusual fish on the water. His father reveals its a colomber, a sort of shark that follows its victim without stopping and can only be seen by the victim and close family. Fearful of the fish devouring his son, the captain will send Stefano away to school.
