If you're not looking to OSRS gold, or are unable to complete that Sea Slug quest, you'll have to go through levels 1 - 20 by fish for Shrimp along with Anchovies. To achieve this, you'll need an Small Fishing Net, and you'll need to travel to the proper fishing spot. The easiest location to access is to the South of the Draynor Bank, whereby you'll discover plenty of net fishing spots. After Level 15. you'll begin to fish Anchovies as well as Shrimp, from the same spot. You'll have to catch 447 Shrimps to achieve enough XP for level 20. In this stage it's time to progress to Fly Fishing. Successfully completing Sea Slug instead, will result in 7.175 the XP needed to go right to the level of 24. So it's highly recommended.

Level 20-58: Trout and Salmon

It is now possible to Fly Fish trout (and Salmon starting at level 30. You'll need a Fly Fishing Rod, plus 1 feather for every fish that you catch so it's recommended that you purchase a few thousand feathers prior to beginning. The most popular place for Fly Fishing is in Barbarian Village, just North-East, on the West bank. The XP rates for this method range from 20 to 45K per hour. The option of dropping the fish and not deposit the fish at the Edgeville bank will increase the rates of XP. It is advised due to the lower worth of Trout and Salmon. As a suggestion that you should consider, you can select an option under the Settings menu which will permit you to press the shift to drop an item instead of 'use the item. This allows you to drop a complete inventory much quicker, and will reduce time spent and increase XP gains. For the level 58. you'll require 224.466 XP . This means you'll need to catch approximately 3.667 fish (trout/salmon combined),

Level 58-99: Barbarian Fishing

You'll need 30 Strength as well as 30 Agility prior to beginning this portion of the training. Then, you'll be able to accomplish a brief miniquest at Otto's Grotto located north of that of the Barbarian Outpost (accessed via Games Necklace). After completing the miniquest, you'll be presented with the Barbarian Rod, which will enable you to learn Barbarian Fishing. Similar to Fly Fishing, Barbarian Fishing requires 1 Feather per fish taken, so be sure to replenish your supplies before heading here. Below level 70. you'll receive about 35.000 to 40.000 hours of experience At the levels of 70 or higher, you will receive around 50.000 to 60.000 experience per hour. When you reach level 99. you'll be able to earn around 60k experience per hour. There is a way to get more xp rates for fishing through 3-tick Barbarian Fishing (up to 110kx/hr at level 99). It is thought to be the quickest and most effective method of teaching fishing, however, some people will find it particularly tedious as there is no money to be made through this method, and you're also required to release each fish because there is no bank nearby. If you are able to endure the monotony, then it's recommend to stick with this method until Level 99. Since the strategies that require banking and profits are particularly inefficient, as is the result not that great in the grand perspective of cheap RS gold everything. However, if you're kind of player that prefers to have OSRS open whilst chilling, maybe watching a film, these alternatives might be the right choice for you.