This guide will show how to survive by fishing (picture by picture as an alternative to the videos).
Guide to Fishing
Craft and Use the Fish Spear
As soon as you have found at least one wood board, some nails and blue tape the fish spear recipe will unlock.
Open the crafting window, select the fish spear, add the materials as required, then select Craft.
The fish spear will appear in your inventory.
Right-click on it and select "Use in hands".
Go to the flat area in water with fish swimming around. On the starter island, this is the area where you can see a barrel floating in the water. This area connects the first part of the island with the next part, which contains a storage barrel and a water barrel.
Wait for one of the bigger fish approaching (they are easier to catch), then left-click. If it does not work with the first try, continue trying. The fish will soon come back. Finally, you will manage to pin the fish with your spear.
At the lower right corner of the screen you can see that you should use "G" to grab the fish from the spear. Use the G and the fish will be in your inventory.
Cook and Eat the Fish
With the fish in your inventory, go to your campfire. If you should not have a campfire yet, follow the steps in the Campfire guide, because you need a burning fire to make the fish eatable.
Open your inventory and right-click on the fish, then select "Unpack" to get fish meat.
Right-click on the fish meat and select "Use in hands", then close the inventory.
If you hover the ghost fish meat piece over the campfire, you can then place it with left-click when the fish is at the correct location in the fire.
Repeat the steps until you placed all fish meat on the fire.
Watch the fish meat carefully. When the white help text switches from "raw fish meat" to "fish meat cooked", take the cooked fish with "F".
If you waited too long, the fish meat will be burnt and you cannot eat it and have to throw it away.
You can see the difference: When you right-click on the burnt fish meat, you will not get the "Use in hands" selection. The two screenshots show the difference.
To eat the cooked fish, right-click on it, select "Use in hands", then close the inventory again.
As the text in the lower right corner of the screen tells you, hold "E" to eat the fish.