1.1. Getting the Necessary Items Edit
First, find a shop that sells basic fishing tools (eg. at Taverly). Buy a fishing net, lobster pot, and a harpoon. These items can be added to your tool-belt, allowing you to gather more fish per inventory.
1.2. Training Edit
1 to 40 EditTeleport to Draynor Village, then proceed to go to the following location on the map.Here, you can fish shrimp and anchovies. Leveling isn't very slow, so you can stay here until you reach 40 fishing. It will not take over 10 minutes.
41 to 50 EditOnce you get 40 fishing, teleport to Catherby. This is a great location to cage-fish and harpoon; there is a bank within 20 seconds of walking distance. From levels 41to 50, catch lobsters.
50 to 76/85 Edit
After getting 50 fishing, start harpooning for tuna and swordfish. Tuna gives a little less XP than lobsters, but swordfish gives a little more, giving you a little more XP per hour and more money if you plan on selling it. You can harpoon until level 76 fishing and move on to catch sharks, or you can keep harpooning until you level 85 fishing.
1.3. Living Rock CavernsEdit
Once you reach level 85 fishing, you should head over to living rock caverns
The Living Rock Caverns (LRC) is the best location to train from 85 to 99 fishing. Living Rock creatures will attack you within the area. It is recommended that you bring a few prayer pots and a pieces of food. There is a nearby deposit box to bank your fish. (How to get to living rock caverns). Home teleport to Edgeville using the lodestone network. Once you're there, walk to the Dwarven Mine entrance as shown on the map. Go down the ladder, and once you are in the Dwarven mines, Simply go south a few steps and the rope to climb down should be right there, on the left.
Once you're in the Living Rock Caverns, start fishing cavefish from 85 to 90 fishing. You will need fishing bait.
From 90-99, you'll be fishing rocktails. You need living rock minerals to catch any. Living rock minerals may be obtained from killing Living rock creatures and mining their corpses. You'll need 77 mining to obtain living rock minerals from the creatures.