There are two ways to catch fish: you can use a fishing rod with a lure or a fishing net.
 
Fishing with a lure
  • Tap on an area that is available for fishing.
  • Select a lure.
  • Cast the line.
  • Use the fish button to keep the line inside the green section of the bar until the time runs out.
If the fish escapes, you will need to start all over. In this case you will be able to reuse the same lure.
Once you catch a fish, the fishing area will temporarily become unavailable.
 
Fishing with a net
 
The Net Maker will be available at level 29.
Tap on an area that is available for fishing, select a net, and be patient.
 
In 20 hours you will be able to retrieve your net, and find out what you caught. In addition to fish, you might be able to catch other items such as decorations, materials and tools.
Tap the item to collect.
The fishing area will be ready to for use as soon as you pull out the net.