Start fishing tuna
Now that your level 20 fishing I suggest to go grab your fly fishing rod and some feathers and start fishing trout at the river in Jade Dynasty Gold or at Barbarian Village Once your level 30 you will catch a mixture of trout and salmon, which is great news! Continue fly fishing until you reach level 40. If you want you can start fishing tuna at level 35 fishing. You can fish them on the dock at Karamja with a harpoon.