For all you hardcore fishers out there the title available in Wrath, "Salty [player name]", is something you must obtain. Most hardcore fishers will have the crawdad pet already so the only really tough part will be completing "The One That Didn't Get Away" which involves catching ONE of the rare fish listed in the achievement.
Now all of these fish are quite rare and have a small chance of dropping, however, there is one fish on the list that seems to have the best percentage from what I've seen and a nice secluded area for fishing, for alliance and horde alike.
In Dun Morogh there is the frozen lake where alliance can learn low level fishing, well in that lake you have the chance of catching the rare 15 Pound Mud Snapper.
The best part about this is no one is ever around this area except the occasional lowbie who probably won't pay attention to you. The seclusion also makes it a nice spot to bot at if you feel like it, though if you are horde there is a good chance that a random bypasser may gank you while you are away.
I was lucky enough to get mine in around 400 casts and I haven't even completed my 1000 caught fish yet. Most may not be as lucky, however, due to the zone level and decent seclusion it makes for a prime spot to complete this achievement.
Good luck!
**I ran a search and could find nothing of this achievement at all