Lonewulfe:
You must be level 35, and have a skill of fishing at 225.
Visit Lumak the fishing trainer in Orgrimmar (in the valley of Honour).
You get sent to Dustwallow Marsh and then sent around to different places to catch rare fish. I recommend you get coords on those fish instead of just going randomly. It can go quickly if you know where you need to be casting.
The Nat Pagle quest is open to both factions. So, drag your hides over and get the quest to go fishing for rare fish.
Coords are as follows:
Just outside Theramore between the coast of Dustwallow and Theramore Isle on a small island.
Nat Pagle is at -59,60
Nat Pagle map location
Feralas Ahi - Anywhere in the river, even near Camp Mojache.
62,51 -in Feralas
Savage Coast Blue Sailfin , Anywhere along the Savage Coast (west coast STV).
34,31 -Stranglethorn Vale
Sar'theris Striker, Anywhere along Sar'theris Strand (just outside Shadowprey Village).
26,76 -in Desolace
Misty Reed Mahi Mahi - Anywhere along the beach in SoS.
80,94 -Swamp of Sorrows
Once you have all 4 fish:
Back to Nat Pagle @ 59,60
If you want a nice fishing pole:
To get the "Big Iron Fishing Pole" you need to go off the shore of Shadowprey Village in Desolace. Bring some water breath pots or spell or seal form or something and swim around opening the "Shellfish Traps". Chances are you will end up having to fight a 33-34th level crawfish that crawls out of the trap when you open it OR shellfish. A rare drop out of shellfish trap is the +20 pole your after.