Green’s Dictionary of Slang

fish n.2

also fisher
[fish v.1 (1)]

(US campus) a toady, a sycophant.

[US]Monthly Anthology I 153: You besought me to respect my teachers, and to be attentive to my studies, though it shall procure me the odious title of a ‘fisher’ [DARE].
[US]B.H. Hall College Words (rev. edn) 200: fish, fisher. One who attempts to ingratiate himself with his instructor, thereby to obtain favor or advantage.