I'll add a third possibility to what Michael suggested for how
to deal w/ the prepositions at the end of "While he is there, he learns
to fish for other things than fish."
 
"other" is and adjective for "things," which is the object of the
preposition "for."  I see "than" as a preposition (roughly meaning
"besides") with "fish" as its object.  The entire prepositional
phrase "than fish" would thus be modifying "things"--semantically,
the phrase restricts the meaning of "things."
 
Larry Beason
Eastern Washington University