Saw this on some other forum so will paste it here.

Level 1-6

Use any rod with little worm in Windurst waters to catch crayfish and the occasional moat carp.

level 6-10

Buy a stronger rod(I recommend Composite Rod because this doesn't break and will last you a long time) Either buy a sakbigi rig or use lug worms with the rod and fish in any area where there are bastore sardines and quus. Almost all low level salt water areas will have these fish. Heres a list of a few of these places, west sarubartha, port windurst, east sarubartha, melbina, mhaura, and etc.

level 10-21

It time to move to East Ronaflaure. Buy yourself some fly lures. They only cost 300gil each at the fishing guild. Use your composite rod with the fly lure to catch cheval salmon and shining trout in East Ronafalure.

level 21-30

Now move back to Windurst. If you exit windurst from port windurst into W. Sarubartha, and move north. You will see a small moat on your right. This moat contains Giant Catfish and Dark Bass. They capp at level 31 and 33 respectively. Go buy yourself a sinking minnow and start fishing there. The sinking minnow will catch both of those fishes. Frog lure will also work, but is more expensive than the sinking minnow lure.

level 30-40

Its time to move to Bastok now. Take the ferry route to Bastok so it will give you a chance to pick up some cheap Sinking Minnow Lures on the ferry. The shop on the ferry sells Sinking Minnows for 600-700gil each. Buy at least 5-10 of these lures as you will be losing some where you will be fishing next. Once you have arrived at Bastok, go out to S. Gustaberg and use your Composite/Sinking Minnow on the East shore line to catch Ogre Eel(35), Gold Lobsters(46), Zalmug Bass(48), and Bastore Bream(70).
You will snap your line and lose some lures here. The Bastore Bream seem to be the fish that is snapping your line because they are too high a level, but that is fine because the fish you get from here will more than cover the cost of the lures. Gold lobsters sell for 430 each and bastore bream sell for 1350 each.

level 40-50

Now its time to move back to windurst. Go to the fishing guild and buy yourself a worm lure. Head out to East Sarubartha Lake and use Composite/worm Lure to catch Monke-Onke(51).

level 50-55

Go back to Windurst and buy a shrimp lure from the Auction house. Now its time to invest in a more expensive mithran rod. Use Mithran/shrimp lure in windurst woods near the fountain area to catch gold carp(55). This is when the money starts coming in. Gold carp sells for 675 each and this is the only fish u will catch with this combination of rod/lure.

level 55-69

This is when it will slow down consideraby. Go buy a fly lure or two from the fishing guild. Use the Mithran/fly lure at the East Sarubartha Lake to catch cresent fish(69). These fishes are kinda rare so the bite rate will be pretty bad.

level 69-80

Buy yourself alot of Meat Ball lure. Move yourself to North Gustaberg and find the North Gustaberg Cascade. Use a composite/Meat Ball to catch Gavial Fish(80). Do Not use mithran rod, it will break.


level 80-96

Go to port jeuno with your Composite/Sinking minnow lures to catch Black Sole(96). The area where u fish is actually in the waiting area for the airship. So you will need to pay the 200gil and have an airship pass to access this area.

level 96-100

Your really need your lu shangs and level 80 woodworking to be able to gain the last 4 levels. The only fish that capps at level 100 is Titanictus. You can only find this fish on the ship from mhaura to selbina and it will BREAK any rod. You need to use a strong rod/meat ball to catch them.

Summary
Skill - Area - Bait - Rod - Aim
0-6 - Windhurst Waters - Little Worm - Bamboo? - Crayfish
6-10 - Port Windhurst/Selbina - Sabiki Rig - Composite - Quus + Bastore Sardines
10-21 - East Ronfaure - Fly Lures - Composite - Cheval Salmon + Shining Trout
21-30 - West Saru River - Sinking Minnow - Composite - Giant Catfish + Dark Bass
30-40 - South Gusta - Sinking Minnow - Comosite - Ogre Eels, Gold Lobsters, Zafmlug Bass + Bastore Breams
40-50 - East Saru Lake - Worm Lure - Composite - Monke Onke
50-55 - Windhurst Woods - Shrimp Lure - Composite - Gold Carp
55-69 - East Saru Lake - Fly Lure - Mithran - Crescent Fish
69-80 - North Gusta - Meat Ball - Composite - Gavial Fish
80-96 - Port Jeuno - Sinking Minnow - Composite - Black Sole
96-100 - Ship - Meat Ball - Lu Shangs - Titanicus