This short guide explain how fishing works in the Dinkum game.
Guide to Fishing (How It Works)
Wait for your fish to bit the bait.
When the water looks like this press left click only once.
Now the fish is going sicko mode, you can spam left click to reel it faster or else can wait for him to calm down.
When the fish is calmed you can reel him until he goes sicko mode again.
One other thing I noticed is when its in sicko mode, once the tail seems to go under water you can start reeling it in again without the meter coming up. Even though it looks like it is still fighting it will turn and calm down. Good tip on the spam thou!