Larry:

For what it is worth, I did a phrase search on my Twain's World CD-ROM,
and did not locate the quote.

There are multiple references to "fish-hooks" (hyphenated) in:

The Esquimau Maiden's Romance
Roughing It:  Volume II:  Chapter 27
Tom Sawyer Abroad:  Chapter 8
The Mysterious Stranger, Part 8

but none as in your quote.  Suspiciously, (yes, fishy) Twain always used
the hyphenated "fish-hooks" in all these quotes.  Your quote did not have
the hyphenation.

Can we draw conclusions from this?  Probably not.

Michael