Complete description of your issue:
Fishing Schools in the Broken Isles do not have any loot.
They should drop fish and also Luminous Pearl (if achievement http://www.wowhead.com/achievement=10596 is done)
I think everything to do with the artifact fishing pole is bugged currently
How am I supposed to get the artifact of there's no fish.
Ive discovered since creating this ticket that some of the pools partially work, occasionally an item will drop but a lot of empty loot windows as well
The Luminous Pearl can be caught from Runescale Koi school in Suramar, after completing the necessary achievement
you actually can get all the rare fish / get the pole.
just keep fishing in the zone... location does not really matter here.
(you get all rares without a school and even without a "buff")