You only need three things to fish.

A fishing rod.
can be found or stolen in houses, shops, or randomly in the world.
a recipe for this item can be gotten from a quest.
Fishing bait.
Found all over the place, in pretty much any barrel, box or chest.
a recipe for bait is found in the same quest as the fishing rod.
A river, pond, sea, puddle, etc


Fishing is simple.
you hold the rod.
you click to throw out your line.
when your character pulls the rod backwards, click again.
If you clicked at the right time, a minigame will start
simply keep your cursor on top of the fish
if succesful (theres a timer) the fish will pop out of the water and into your inventory

There is a steam achievement that needs you to fish up one fish successfully.
Very easy, just fish normally and you'll get it.


The quest to unlock the fishing rod and bait can be found SOUTH WEST of pop pop's shop plot. Directly WEST of the farm quest. There is a teleport totem nearby named Jones Fishingmans House.
He will ask you to collect 5 raw crab meat. there are crabs right by his house, on the beach.