This page of the Valheim guide provides instructions on how to fish and what types of fish species you may encounter in the game. Catching fish in Valheim is not that obvious. During storms, there is a chance that the rough sea will wash up some fish that you can simply pick up. However, fishing remains the default way to obtain fish.
How to fish with a fishing rod?
To start fishing, you will need a rod and some bait. Both items can be obtained at the merchant's.
Once equipped with a rod and bait, hold the left mouse button, aim and release it. The longer you hold the button, the further the float will go.
Wait for the fish to take the bait. This will be indicated by a distinctive sound, movement of the float, and a blue "shock wave" around the float. You must then press and hold the right mouse button until your character reels the fish in and drags it ashore.
Note: reeling in a fish will drain your stamina. If you don't get the fish out before your stamina runs out, the fish will escape. That's why it's better to avoid casting your rod farther when you aren't full.
What can you catch?
At the moment, there are only 3 types of fish in Valheim, which differ only in the number of pieces of fish you obtain after picking them up.
The smallest fish give you 1 piece of fish, the medium-sized fish - 2 pieces, and the largest fish - 4 pieces.