The Fast Fish And Loose Fish site is a little closer to home than what I tend find with my random Next Blog>> researches, but as obscure as I find that Fast/Loose dichotomy, I do love the idea that Melville is propounding:
The word "fast" in Moby-Dick means that a whale has been captured, while for Melville the word "loose" implies that the whale is still free. Moby-Dick himself was the biggest loose fish, still loose at the end of the novel.
Then, Melville expands to politics -- which countries in 1851 were fast fish and which ones were loose fish? Imperialism and colonization were huge issues for him.
"What was America in 1492 but a loose-fish, in which Columbus struck the Spanish standard by way of waifing it for his royal master and mistress? What was Poland to the Czar? What Greece to the Turk? What India to England? What at last will Mexico be to the United States? All Loose-Fish.So "stay loose," as the saying goes.
What are the Rights of Man and the Liberties of the World but Loose-Fish? What all men's minds and opinions but Loose-Fish? What is the principle of religious belief in them but a Loose-Fish? What to the ostentatious smuggling verbalists are the thoughts of thinkers but Loose-Fish?
What is the great globe itself but a Loose-Fish? And what are you, reader, but a Loose-Fish and a Fast-Fish, too?"