This is a little trick i found out yesterday and i thought i'd share it with everyone
A lot of people pour countless amounts of gold into getting potions so they can breath underwater to farm this little fishing rod which causes them to lose out on a bigger profit. Yesterday while trying to level up my fishing to use a fishing bot, i decided to get one of these, only i did it without a single pot. How you may ask? Simple, inside of the instance Gnomeregan, there is a boss called the Viscous Fallout. He drops an item called the Hydrocane:
http://www.thottbot.com/?i=6346
This item is PRICELESS because equiping this allows for unending breath! This allowed me to get about 4 poles in ~2 hours and i was able to sell 3 of these for 25 g each!
Happy farming