There are several fishing trips I believe. You can fish on your own from the bank or from a canoe at FW. There is a fishing hole at PO-Riverside. There are also a few actual fishing trips. I think they leave from YC/BC and PO-RS, but I'm not sure. I know you can find the information in WDW for Couples.
There are several fishing excursions, leaving from different sites- Boardwalk, Downtown, Fort Wilderness,Yacht& Beach club, and others. For more info try 407-WDW-PLAY.