Simply click on the fish you can see swimming in the water and your character will begin fishing. If you are fishing actively, when your character reels in a fish it will fly up and bash you in the head, causing damage to your character. Each type of fish requires a certain amount of defense to endure. If your character has enough defense, no damage will be taken.
For example, my fisherman has 26 defense and takes 25 points of damage when hit with a Hermit Can. If you are active fishing and have low defense, make sure to equip food. Fishing does no damage to your character when AFK.
Efficiency works a little different here than in other skills. Besides increasing the amount of fish you get and decreasing your catch time (up to around 5-6k efficiency), Efficiency also affects which fish you get, as it relates to the "depth" at which each fish can be caught.
All 4 small fish can be caught in any of the first five fishing spots (first and second fishing zones).
All 4 medium fish can be caught in any of the final three fishing spots (third fishing zone).
See how I said chance to catch? That's because when you have enough efficiency for the next fish, your percentage for the fish before gets reduced and added to the next.
Another example: My fisherman is level 11 fishing, has 193 efficiency, using fly as bait, Scripticus Spoons line and Copper Fish Rod, my percentages are 68% for Goldfish and 32% for Hermit Can.
Note that each fishing spot has different rates for fish. For example, if you look at AFK gains at the Fishing spot closest to the desert town you will notice that your goldfish gains are different than the second Fishing spot by Whattso.
Apart from fish, you can also get various other items from AFK fishing.
Alongside Fishing Rods, different accessories can be equipped at the Fishing Rack. The four colored Xes increase the chance of catching the fish of that depth. FExp is Fishing Exp, FSpeed decreases time between catches, and FPow is Fishing tool power (increases efficiency). You may have one Fishing Line and one Fishing Weight equipped at a time.
The aim of the minigame is to get as many points as possible by holding on screen (mobile) or holding left mouse button (PC) for the required time, then letting go to cast far enough to land on the fish without hitting a mine.
When your lure lands on a fish you get the corresponding points:
1 point for Green Fish
2 points for Eel
3 points for Squid
5 points for Whale
The more casts you do the harder it gets, the fish targets start to move and more mines will appear on the screen.
After 3 consecutive Green Fish, Eels will start to appear and after 3 more consecutive landings (doesn't have to be Eels) Squid will appear, and finally, after another 7 consecutive landings on any fish makes the Whale appear, catching it will reset your streak back to 1.
To obtain Megalodon trophy you will have to catch two whales in a row, then miss the third one. Then the "behemoth" will appear. Catching it will give trophy.
Upon completing Rift 16 in World 4, Skill Mastery unlocks. Skill Mastery gives you account wide bonuses based on your skill's total level across every player.