[1] Instructors teaching Moby-Dick use the chapter to illustrate one of the book's main themes, the slippery nature of moral principles.
Two simple rules were then formulated as a means of settling arguments over the ownership of a fish, as follows: Ishmael then describes a court case in which the crew of one ship's whaleboat chased and harpooned a whale, but then had to abandon the boat in order to save themselves.
He gives examples of the concept, applying them to instances such as slavery in the United States, serfdom in Russia, British rule in Ireland and the American annexation of Texas.
Ishmael's description initially seems to praise the legal concept as solving whaling disputes peacefully, but the critic John Bryant points to the chapter as an example of Melville's ironic style.
Ishmael gradually converts his initial off-handed meditation on the legal concept of possession into "a more sanguine, indeed calamitous, tirade" on topics such as British rule in India and the US annexation of Mexican territory, and ends with the question of whether the rights of man and the book's readers themselves are fast fish or loose.
[9] One law school instructor wrote that the chapter may be particularly useful in helping students understand the concept fee simple absolute as it relates to a property dispute.