Alliance: Crystal Lake in Elwynn Forest
Horde: The lake at Bloodhoof Village in Mulgore
Alliance: The Canals in Stormwind
Horde: The Pond in Orgrimmar
Fishing 75 - 150:
For this fish the River in Hillsbrad Foothills.
You will need to get and read the Expert Fishing Book that you can buy from Old Man Hemming in Booty Bay on the Lowest level of the town.
Horde: Fish off the pier in Shadowprey Village in Desolace.
Alliance: Fish the lakes around Stromgarde Keep in Arathi Highlands.
At level 225 you will have to go to the islands in Dustwallow Marsh. FSwim SW from Theramore Island to Nat Pagle at 59,60. Get a quest from him called Nat Pagle, Angler Extreme, to catch 4 rare fish.
**One for The Savage Coast in Stranglethorn Vale. Savage Coast Blue Sailfin at 26,20.
**One from the Verdantis River in Feralas. Feralas Ahi at 62,51.
**One from the northern Sartheris Strand in Desolace. Ser'theris Striker at 26,76.
**One from the coastline in Swamp of Sorrows. Misty Reed Mahi Mahi at 80,95.
Upon completion of this quest, Nat Pagle will give you Master Fishing skill raising your cap to 300. After that head to one of the map locations below to level your fishing.
Alliance: Head to Steamwheedle Port in Tanaris and fish along the beach.
Horde: Head to Raventusk Village in the Hinterlands and fish along the beach.
Both Alliance and Horde head to Felwood and fish Bloodvenom Falls.
Both Alliance and Horde go to Azshara and fish around Scalebeard's Cave.
You will need to go get your hands on the Artisan Fishing Book which is obtained from the fisherman at the Cenarion Expedition in Zangarmarsh in the Outlands, just on the bank of the lake. Due to high fishing requirements throughout Outland, it is strongly suggested to have at least a +75 lure and +20 fishing pole whenever possible. A suitable pole is easily obtained from a quest in Lower City in Shattrath, 'Rather Be Fishin'.
Both Alliance and Horde should fish Umbrafen Lakes and The Lagoon in Zangarmarsh.
At 345 head over to Serpent Lake, Sporewind Lake, and Marshlight Lake in Western Zangarmarsh.
Fishing 345-360: This these levels head to Terrokar Forrest and fish the various rivers.
Fishing 360-375: For this both Alliance and Horde will need a flying mount. You have to fish the high altitude lake areas of Terrokar Forrest. Use +100 lures and the strongest fishing pole you can. While some fish will still get away, it will still be the best place to fish, and the Spicy Crawdad sell very well to boot.
In the 3 fly-to-only lakes in Terrokar Forest, there are a total of 17 Highland Mixed School fishing nodes (3 in Lake Jorune above Stonebreaker Point, 4 in Lake Ere'Noru above Allerian Stronghold, and 10 in the Blackwind Lake/Skettis area.) You will need to have about 480 or more fishing to reliably catch the fish in these lakes...being Furious Crawdads, Goldenscale Vendorfish (that vendor for 6g per! ), Golden Darters, crates, scrollcases, and possibly Mr. Pinchy.
(As a side note, Furious crawdads only come from those Highland Mixed Schools, which are used in cooking Spicy crawdad, Which gives you 30 stam and 20 spirit for 30 minutes if you spend at least 10 seconds eating)
Just like there the rare fish in STV during the contest, there is a very small chance that you can catch Mr. Pinchy, a rare Crawdad that will have 3 wishes (charges) that give a random effect/item with a 48 hour cool down from those Highland mixed pools. Mr. Pinchy's drop rate is approximatly 0.2% which averages to about 1 in 500 successful casts. So be prepared to spend a lot of time trying to get him.
If / When you get Mr. Pinchy there are 5 effects of the wishes. These are: Mr. Pinchy's Gift, A gift wrapped package that will have 4-5 Super Healing, and 4-5 Super Mana potions in it. (seems to be the most common result of the wishes) Summon Furious Mr. Pinchy, level 70 Non-elite that will attack you and party. Benevolent Mr. Pinchy, Summons a level 70 guardian to assist you in combat. Mr. Pinchy's Blessing, a 2 HOUR +1200hp buff that lasts even through death. Magical Crawdad Box, The only permanent, non-consumable reward, a uber-rare non-combat pet (normal white quality, but uber rare because you have to catch Mr. Pinchy in the first place to get it, and then be lucky enough to get him to give you the pet after that. After using the 3rd Charge/wish Mr. Pinchy will disappear from your inventory, having been consumed. You will have to catch Mr. Pinchy again in order to get another 3 wishes/chances to get what you are looking for, which for most people is the Magical Crawdad Box.
How to get 527 Fishing:
375 Base Fishing Skill
+40 Arcanite Fishing Pole (+35 from the pole, +5 from putting the High Test Eternium Fishing Line on it for total of +40)
+5 Lucky Fishing Hat
+5 Nat Pagle's Extreme Anglin' Boots
+2 Fishing Skill Enchant to gloves
+100 Aquadynamic Fish Attractor (lure)
At Fishing Level 525 or higher, you will stop seeing "your fish got away!" messages no matter where you go, including the 3 fly-to only lakes in Terrokar Forest which have the highest fishing requirement and best fished items in the game.
427 is the highest fishing skill you can have un-lured (same as above, but with the +2 fishing skill to glove enchant as well), which makes the in-game cap for fishing 527 with an aquadynamic fish attractor.