I did a search for this topic and didn't find any concerning this bug, so here i go trying to not become a leecher
In the daily fishing quest "Crocolisks in the City" (Crocolisks in the City - Quest - World of Warcraft), given by old man Barlo at silmyr lake just north east of shattrath city, you are tasked to catch "Baby Crocolisks" in both orgrimar and stormwind.
You will catch these at pretty much first cast, and requires only lvl one fishig lvl.
Now here's the bug, somehow the quest alters the loot chances of fishes that you are going to catch, when adding baby crocolisks to the loot table. For some reason, the catch chance of old crafty then becomes EXTREMELY high.
So here's how you do it:
1 - Get the daily quest of Old Man Barlo. You may have to wait a few days for it to appear, as it cycles between 5 daily fishing quests every day.
2 - Go to Orgrimar (for this to be easier for alliance use the quest talked about in the thread which is named "Easier Old crafty" or something)
3 - Fish in any pool
Now, at probabbly every catch, you will catch a baby crocolisk and another random fish. DO NOT LOOT THE CROCOLISK, turn auto loot off, and if you do loot it, delete it (although i am unsure of what effect that has on this bug). The other fish that appears has an extremely high chance of being old crafty, but some have reported that it took them up to 30 casts to get him/her, so don't panick if you don't get him/her within the first 5 casts. If it's not old crafty, do not loot the other fish, i am unsure of how this affects the bug, and 1-30 missed lvl 1 fishes won't do you any harm.
Il put a pic up here of my old crafty (I'm alliance), later, i caught him 3 days ago, so let's hope this didn't get fixed during maintenance.
(my character is in the process of a server transfer, so i don't know how long it will take to get that pic up here)
PS: This does NOT work for Ironjaw in IF, as you cannot catch baby crocolisks there. But fear not, these two fishes aren't needed for the "accomplished angler" achievement anyways.
Happy fishing!