This October? You may be a cutting it a little close. Fish Extenders are handled on your Cruise Meet thread. IF your cruise has a thread, and IF the group sets up a Fish Extender exchange.
Go to the Cruise Meet board (link at top of thread on main page here) and look for the "Find your (YEAR) (ship name) Cruise Meet LINK here" thread. Click on that and scroll through the first post there to see if your cruise has a link listed. If so, click on that link and ask if there's a FE group set up.
Note, not all cruises have a Cruise Meet Thread. And not all Cruise Meet Threads have Fish Extender groups. There may be Fish Extender groups on other social media sites, but they are not DISboards connected and links to those cannot be posted on DISboards.
