Weather-Beaten Journal

When used, the Weather-Beaten Journal teaches the player Find Fish, the ability to observe fishing spots on the mini-map in the same manner as the herbalist's ability to see herb nodes. This is the only way to gain the ability.

Source
Weather-Beaten Journal can be looted:
 * from within containers fished in Kalimdor, the Eastern Kingdoms, and Outland, most commonly from pools such as Floating Wreckage;
 * from within bags rewarded from daily fishing quests in classic capitals, from Old Man Barlo (near Shattrath City, Outland), or in Draenor Garrison;
 * from any fish pool on the Broken Isles.

To be eligible to loot journal character must have at least 1 skill point in the Fishing skill. If you already have the Find Fish ability you won't see any additional Weather-Beaten Journals.